MONTREAL - An envelope addressed to Luka Rocco Magnotta which was later found to contain a suspicious powder prompted authorities Tuesday to shut down one of Canada's biggest postal centres.

The incident began after an employee at the Montreal plant spotted Magnotta's name as the addressee and brought the letter to a manager, said Alain Duguay, the president of the facility's union local.

Police were called to the distribution centre, which handles much of the mail for Eastern Canada. Duguay said an officer unsealed the envelope to find a white powdery substance inside.

"That's when they set up a security perimeter and quarantined some people," he said of the police reaction, which involved about 15 employees and brought operations to a halt for two hours.

Police determined the substance was not dangerous, but four people — two workers and two managers — were treated for what Duguay described as adverse psychological reactions.

Magnotta is facing multiple charges, including first-degree murder, in the death and dismemberment of Montreal student Jun Lin. He has also been charged with shipping some of Lin's body parts through the mail.

In May, workers at an Ottawa postal warehouse found a parcel containing Lin's severed hand — addressed to the Liberal party.

The 29-year-old porn actor has pleaded not guilty to all counts.

Canada Post does not have a protocol to intercept letters addressed to Magnotta, so Duguay praised the employee's decision to alert management.

"We know that there are investigations on Mr. Magnotta — I think it was legitimate," said Duguay, who couldn't say whether the envelope was addressed to the Montreal detention centre where Magnotta is locked up pending trial.

"I don't think one can ever take too many precautions."

Neither Canada Post nor Montreal police would confirm whether the letter was addressed to Magnotta.

But Const. Anie Lemieux, a police spokeswoman, said the force has launched an investigation.

"It's something that they will look into," Lemieux said of the possible Magnotta connection.

"Our investigators are looking to see where this envelope came from, what the content was exactly, who it was (addressed) to."

A few hours after the envelope was discovered, a Canada Post letter-carrier depot in the Montreal-area community of Ste-Julie was also evacuated when staffers there found a suspicious powder. The substance was in a mail bin that came from the Montreal sorting centre.

The Ste-Julie warehouse was shut down for several hours and officials later determined that the substance was not hazardous, a spokeswoman for Canada Post said.

Anick Losier did say, however, that five employees in Ste-Julie were taken to hospital as a precaution because they were feeling ill following the incident.

Due to the incident, Canada Post cancelled mail delivery Tuesday in Ste-Julie and the nearby community of St-Amable.

At the Montreal centre, Losier said one employee reported redness on her skin after she came into contact with the substance found in the letter.

She said she doesn't expect the shutdown of the Montreal distribution centre, a plant of nearly one million square feet, to cause a major slowdown for operations.

"Tomorrow, (it) should be back to normal."

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  • Photos from the family of Jun Lin, the victim of Luka Magnotta were given to media Tuesday, April 2, 2013 in Montreal. Preliminary hearing is underway for Luka Rocco Magnotta, the man charged in connection with the infamous body-parts case that made international headlines.

  • Photos from the family of Jun Lin, the victim of Luka Magnotta were given to media Tuesday, April 2, 2013 in Montreal. Preliminary hearing is underway for Luka Rocco Magnotta, the man charged in connection with the infamous body-parts case that made international headlines.

  • Photos from the family of Jun Lin, the victim of Luka Magnotta were given to media Tuesday, April 2, 2013 in Montreal. Preliminary hearing is underway for Luka Rocco Magnotta, the man charged in connection with the infamous body-parts case that made international headlines.

  • Photos from the family of Jun Lin, the victim of Luka Magnotta were given to media Tuesday, April 2, 2013 in Montreal. Preliminary hearing is underway for Luka Rocco Magnotta, the man charged in connection with the infamous body-parts case that made international headlines.

  • Photos from the family of Jun Lin, the victim of Luka Magnotta were given to media Tuesday, April 2, 2013 in Montreal. Preliminary hearing is underway for Luka Rocco Magnotta, the man charged in connection with the infamous body-parts case that made international headlines.

  • Photos from the family of Jun Lin, the victim of Luka Magnotta were given to media Tuesday, April 2, 2013 in Montreal. Preliminary hearing is underway for Luka Rocco Magnotta, the man charged in connection with the infamous body-parts case that made international headlines.

  • Photos from the family of Jun Lin, the victim of Luka Magnotta were given to media Tuesday, April 2, 2013 in Montreal. Preliminary hearing is underway for Luka Rocco Magnotta, the man charged in connection with the infamous body-parts case that made international headlines.

  • Photos from the family of Jun Lin, the victim of Luka Magnotta were given to media Tuesday, April 2, 2013 in Montreal. Preliminary hearing is underway for Luka Rocco Magnotta, the man charged in connection with the infamous body-parts case that made international headlines.

  • Photos from the family of Jun Lin, the victim of Luka Magnotta were given to media Tuesday, April 2, 2013 in Montreal. Preliminary hearing is underway for Luka Rocco Magnotta, the man charged in connection with the infamous body-parts case that made international headlines.

  • Photos from the family of Jun Lin, the victim of Luka Magnotta were given to media Tuesday, April 2, 2013 in Montreal. Preliminary hearing is underway for Luka Rocco Magnotta, the man charged in connection with the infamous body-parts case that made international headlines.

  • Luka Rocco Magnotta is shown in an artist's sketch in a Montreal court on Wednesday, March 13, 2013. Magnotta has collapsed in court during his preliminary hearing.The notorious suspect in a killing and dismemberment case had been listening to evidence against him, whose contents are subject to a publication ban.

  • Daran Lin, father of murder victim Jun Lin, leaves the courthouse in Montreal on Tuesday, March 12, 2013. Preliminary hearing is set to start for Luka Rocco Magnotta, the man charged in connection with the infamous body-parts case that made international headlines.

  • Luka Rocco Magnotta is seen in an artist's sketch in a Montreal court on Monday, March 11, 2013. A preliminary hearing is set to start for Magnotta, the man charged in connection with the infamous body-parts case that made international headlines.Magnotta's lawyers want the public and media barred from attending the hearing, which is to determine if there is enough evidence for a trial.

  • Daran Lin, father of murder victim Jun Lin, leaves court with his translator Daran Lin in Montreal on Tuesday, March 12, 2013. Preliminary hearing is set to start for Luka Rocco Magnotta, the man charged in connection with the infamous body-parts case that made international headlines.

  • Alleged killer Luka Rocco Magnotta is seen in court on a artist drawing Wednesday, January 9, 2013 in Montreal. Magnotta is charged with first-degree murder in the slaying and dismemberment of Chinese engineering student Jun Lin.

  • Luka Rocco Magnotta is taken by police from a Canadian military plane to a waiting van on Monday, June 18, 2012 in Mirabel, Quebec. Magnotta, the lone suspect in a brutal Montreal killing that made headlines around the world, is back home to face justice on Canadian soil. (Montreal Police)

  • Magnotta lands in Canada (Montreal Police)

  • Magnotta lands in Canada (Montreal Police)

  • Mug shot of Luka Rocco Magnotta, released by Montreal Police on Tuesday, June 5, 2012. Magnotta told a judge Tuesday he will not fight his extradition from Germany to Canada, Berlin police say. Magnotta is wanted in Canada on several charges, including first-degree murder, in connection with the killing and dismemberment of Chinese national Jun Lin. (AP Photo/Montreal Police Service via The Canadian Press)

  • Vancouver Police Deputy Chief Warren Lemcke speaks during a news conference after a human hand was delivered to a school and a human foot to another in Vancouver, B.C., on Tuesday June 5, 2012. Montreal police later confirmed the packages are connected to the dismembered body of a Chinese student found in Montreal last week and the international manhunt for his killer. (THE CANADIAN PRESS/Darryl Dyck)

  • A man walks his dog past St. George's School where a human foot was delivered to the school earlier in the day in Vancouver, B.C., on Tuesday June 5, 2012. A human hand was also delivered to another Vancouver school Tuesday. (THE CANADIAN PRESS/Darryl Dyck)

  • A television cameraman films parents and students at False Creek Elementary School after a human hand was delivered to the school earlier in the day in Vancouver, B.C., on Tuesday June 5, 2012. A human foot was also delivered to another Vancouver school Tuesday. (THE CANADIAN PRESS/Darryl Dyck)

  • A police car leaves the central police detention facility of Berlin supposedly carrying Luka Rocco Magnotta to a Berlin court Tuesday, June 5, 2012. Luka Magnotta, 29, a Canadian porn actor suspected of murdering and dismembering a Chinese was arrested on Monday at an Internet cafe. A cafe employee recognized Magnotta from a newspaper photo and flagged down a police car. (AP Photo/dapd/ Timur Emek)

  • The internet cafe where Luka Rocco Magnottahe was recognized in the district of Neukoelln in Berlin, Germany, Monday, June 4, 2012. (AP Photo/Markus Schreiber)

  • This image taken from CCTV obtained by Associated Press video shows Luka Rocco Magnotta entering the Internet cafe in the district of Neukoelln in Berlin, Germany, Monday, June 4, 2012, where Kadir Anlayisli, who works in the cafe recognized him. "I looked at him and thought I knew him from somewhere, because I read newspapers every day," Anlayisli said. (AP Photo/AP Video)

  • This image taken from CCTV obtained by Associated Press video shows Kadir Anlayisli, a cafe worker waiting for police in the doorway of the Internet cafe in the district of Neukoelln in Berlin, Germany, Monday, June 4, 2012, where Luka Rocco Magnotta was arrested. (AP Photo/AP Video)

  • This image taken from CCTV obtained by Associated Press video shows police entering the Internet cafe shortly after. (AP Photo/AP Video)

  • This image taken from CCTV obtained by Associated Press video shows Luka Rocco Magnotta, 2nd left, being removed by police from the Internet cafe. (AP Photo/AP Video)

  • Kadir Anlayisli stands next to the computer where he recognized Luka Rocco Magnotta. (AP Photo/Markus Schreiber)

  • The Interpol alert, which shows various photos and a discription of Luka Rocco Magnotta. (AP Photo/Interpol/dapd)

  • This surveillance image provided by Interpol shows Luka Rocco Magnotta at a security checkpoint. (AP Photo/Interpol)

  • In a Wednesday, May 30, 2012 photo, janitor Eric Schoer looks at a blood-stained fridge at an apartment rented by suspect Luka Rocco Magnotta, where police believe a man was murdered and dismembered, in Montreal. (The Canadian Press, Ryan Remiorz)

  • A police officer removes a package containg a human foot from the Conservative Party headquarters in Ottawa on Tuesday, May 29, 2012. (THE CANADIAN PRESS/Sean Kilpatrick)

  • The following is a series of photos and self-portraits posted by Magnota on various websites (Facebook)

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  • (http://luka-magnotta.com)

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