Ottawa Police gave the all-clear shortly after 5 p.m. ET on Twitter.
"Situation resolved on Parliament Hill. Package examined and non-hazardous," the force tweeted.
The RCMP said tests did not turn up any hazardous substances.
"Just been advised the package was deemed to be negative," RCMP spokeswoman Cpl. Lucy Shorey said in an email.
"We cannot comment further on this matter as it is currently under investigation."
The Mounties were called in shortly before 3 p.m. ET after a package was left outside the Centre Block, Shorey said.
Hazardous-material crews and paramedics were also on the scene.
Shorey said six people who came into contact with the package — a mix of Parliament Hill security guards and RCMP officers — were isolated as a precautionary measure, but all are fine.
"They're all being monitored, they're all fine at this time," Shorey said.
Police secured the area around Centre Block, including the base of the Peace Tower, and blocked access to the building, which is also home to the House of Commons and MPs' offices.
Hazardous-material crews and firefighters walked in and out of a brown tent erected outside the building.
A clear box contained what appeared to be a newspaper.
The incident follows another package left this week in a downtown Ottawa building housing the offices of the Public Safety Department, just five blocks from Parliament Hill.
A fire department hazardous materials team secured that package from earlier this week and determined its contents were non-hazardous.
The Centre Block was briefly evacuated last spring after security guards spotted a suspicious truck parked behind the building. The RCMP's bomb squad was called in, and gave the all-clear a short time later.
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