But police Chief Rod Knecht told a news conference late Tuesday night that there is no suggestion of gang involvement and the motive for the "senseless mass murder" appears to have been "planned and deliberate" domestic violence.
"It's terrible for the city," said Knecht. "The scene ... has been described as chaotic, horrific. Particularly when there's children involved, it has a tremendous impact on our folks."
Although he did not release the name of the suspect, Knecht said the man had a criminal record dating back to September 1987 involving drugs and violence.
Cyndi Duong, 37, was fatally shot in a home in south Edmonton on Monday while two men and three woman between the ages of 25 and 50, and a girl and a boy — both under the age of 10 — were found dead a few hours later at a home in the northeast.
Investigators have determined the 9 mm handgun used in the killings was a registered weapon that had been stolen in Surrey, B.C., in 2006.
The suspect was found dead by his own hand in a restaurant in the Edmonton bedroom community of Fort Saskatchewan on Tuesday morning.
Autopsies will be conducted on Thursday.
Knecht said it all started when police responded just before 7 p.m. Monday to a report of a man entering the south-side home, opening fire and fleeing. That's where Duong's body was found.
An hour and a half later, officers responded to reports of a suicidal man at a northeast residence, the same home where a man had been arrested in November 2012 and charged with domestic and sexual assault.
Family members reported in the call that the man was "depressed and over-emotional."
When officers arrived, Knecht said, no one answered the door. They searched the exterior of the home but found nothing overtly suspicious and did not go inside.
"We can't just arbitrarily go into that residence," explained the chief. "(Officers) did a walk-round, looked in a window and checked a door."
Hours later police were contacted by a second person and returned to the residence. When they went inside, what they found was carnage.
Knecht allowed that officers would have had information about a previous domestic violence incident at the home but said that still would not give them cause to enter on the first contact.
"We did everything we could have done," he insisted.
Neighbour Moe Assiff watched what unfolded as police arrived on scene the second time.
He said a man and a woman sitting outside the house in a white car seemed very concerned. He said he went up to the car and talked to the man to see if everything was OK.
"He looked very shaken up like he had seen a ghost. He paused and he said, 'No, it's personal,'" said Assiff.
He saw officers come out and talk to the woman in the car.
"She just let out a hysterical scream. It was eerie," he said.
"She was screaming about her kids: 'My kids! The kids!,' grabbing her hair and trying to pull her hair out. The cops then ushered her down the road into a police cruiser."
The suspect's body was found hours later at the VN Express Asian restaurant in Fort Saskatchewan after police brought in tactical-team officers, surrounded the area and reportedly smashed through the front of the restaurant with a vehicle. The front door of the building was knocked out and pieces of the metal frame hung from above.
Knecht said the man had a business interest in the restaurant, but would not say if he was the owner.
Outside, was parked a black SUV police say was seen near the first shooting is southwest Edmonton.
Alberta Premier Jim Prentice said in a statement that he trusts the police investigation will provide answers as people struggle to understand what happened.
"In this season of peace and goodwill, this act of violence is all the more difficult to comprehend. Our thoughts and prayers are with the families and friends of those involved at this very difficult time. May they find strength in knowing that Albertans share in their loss."
At their game on Tuesday night, the Edmonton Oilers paused for a moment of silence out of respect for the victims.
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