Ten people were killed and 15 others were injured after a white rental van mowed down pedestrians along a busy street in Toronto on Monday.

The incident happened at around 1:30 p.m. on Yonge Street, starting at Finch Avenue and ending near Sheppard Avenue, about two kilometres away, where a police officer arrested a male suspect without firing a single shot.

Toronto Police Chief Mark Saunders identified the suspect as Alek Minassian, 25, of Richmond Hill, Ont.

Saunders told reporters at a press conference Monday that investigators were working hard to determine a motive, and that Minassian was not known to Toronto police.

“There’s nothing on our files,” he said. “There’s nothing that we have on him right now.”

Minassian’s neighbours told CTV’s Peter Akman that they would see him jogging and that he kept to himself. One former classmate said he struggled with mental illness.

National security sources told CTV’s Mercedes Stephenson that mental health was the primary focus of the police investigation, and that they had found no indication of radicalization.

Saunders encouraged members of the public who may have information to call an investigative hotline at 416-808-8750. He said those affected by the tragedy should contact victim services at 416-808-7066.

Witness Ali Shaker, who was driving southbound on Yonge Street at the time of incident, said the van sped along a sidewalk, hitting at least one stroller and “crumbling down people one by one.”

Carol Roberts, who witnessed the aftermath, said she saw “a lot of people lying lifeless on the ground.”

“It was just so many bodies,” she told CTV News Channel.

A witness named Kash told local news station CP24 that he was having lunch at a Jack Astor's restaurant when he came out and saw four bodies on the ground in front of Mel Lastman Square.

“People were trying to revive them obviously to no avail,” he said.

“It seems very clearly that the van had hopped the curb and kind of driven on the sidewalk going southbound and hit plenty of people.”

Kash said that it was “very traumatic.”

“Our thoughts and prayers go to people that do have family that have been hit,” he said.

“There was a guy here who said he followed the van down honking his horn trying to warn people as much as he could," he added.

Arrest caught on video

A video shared with CTV News shows a tense standoff between a police officer and the suspect, who is holding an object in his hands.

“Get down!” the officer is heard shouting.

“I have a gun in my pocket,” the suspect can be heard saying.

“Get down or you’ll be shot!” the officer yells.

The camera turns away from the confrontation for approximately eight seconds, then looks back to show the suspect on the ground, face-down, with the officer cuffing him.

Chief Saunders said that there was no indication that the suspect had a gun.

Victims in critical condition

Saunders offered no details on the 10 deceased victims and said that the majority had not yet been identified.

Earlier on Monday, Dr. Dan Cass of Sunnybrook Hospital told reporters that the trauma centre had received a total of 10 adult victims.

Dr. Cass said that two of the victims were pronounced dead upon arrival, five were in critical condition and three were in serious condition.

He said that people seeking information on patients should call 416-480-4940.

Invesco Canada President Peter Intraligi said that two Invesco employees were injured. The Toronto Public Library said all of its employees who were working at the North York Central branch have been accounted for.

Pedestrians struck in Toronto

Jesse Tahirali / CTV News. Source: Google Maps

Toronto map of van-pedestrian incident

Politicians react

Prime Minister Justin Trudeau called the incident “a tragic and senseless attack.”

“On behalf of all Canadians, I offer my heartfelt condolences to the loved ones of those who were killed, and my thoughts for a fast and full recovery to those injured,” he said late Monday.

“We are monitoring this situation closely, and will continue working with our law enforcement partners around the country to ensure the safety and security of all Canadians,” the prime minister went on.

Ontario Premier Kathleen Wynne called it a “tragic situation,” and thanked first responders.

“This is a frightening thing that is not emblematic of who we are as a city or a province, but a tragedy that we will work through,” Wynne said. “But there will be a lot of sadness and pain before that happens.”

With reports from CTV’s Peter Akman, CTV’s Genevieve Beachemain, CTV’s Mercedes Stephenson, CTV’s John Vennavally-Rao, CTVNews.ca’s Josh Elliott, CTV Toronto and CP24