Canadian police are questioning the suspected driver of a rented van that ploughed into pedestrians in northern Toronto on Monday, killing 10 and injuring 15.
Alek Minassian, 25, was not previously known to authorities, police said.
The incident appeared to be deliberate but the motive was not clear, officials added.
Canadian Prime Minister Justin Trudeau said the “tragic and senseless attack” had brought him “great sadness”.
Meanwhile, an officer has been praised for not opening fire during a tense standoff with the suspect, who claimed to be armed.
The officer tells the man to “get down” and when the suspect says he has a gun, the officer repeats: “I don’t care. Get down.” The suspect was then arrested without shots being fired.
How did the incident unfold?
Police said the white rental van mounted the kerb on Yonge Street between Finch Avenue and Sheppard Avenue at about 13:30 local time (17:30 GMT) on Monday and drove into pedestrians along a 2km (1.24 mile) stretch.
He said the van was repeatedly mounting the pavement and running into people.
- ‘It was awful’: What eyewitnesses saw
One witness told City News that the driver was “hitting anything that comes in the way”.
“People, fire hydrants, there’s mail boxes being run over,” said the unnamed man, who said he was driving behind the van during the incident.
As the van continued, the man said he sounded his horn to try to warn pedestrians. “I witnessed at least six, seven people being hit and flying in the air, like killed, on the street,” he said.
Pictures from the scene showed bodies covered in orange sheets along the van’s route. Debris and items of clothing were scattered across the pavements and road.
The van was brought to a halt by police several streets away and was quickly surrounded.
What is known of the suspect?
Very few details have been released about the man being questioned.
Police said Alek Minassian was from the northern Toronto suburb of Richmond Hill.
Toronto Police Chief Mark Saunders told a news conference that he was not previously known to authorities.
“The actions definitely looked deliberate,” he said, adding that it was too early in the investigation to say whether the incident was terror-related.
What else is known?
Van rental company Ryder System Inc confirmed that one of its vehicles was involved and said it was co-operating with authorities.
The incident happened while foreign ministers of the G7 leading industrialised nations – Canada, the US, Britain, France, Germany, Italy and Japan – were holding talks in Toronto.
Canadian Foreign Minister Chrystia Freeland said the G7 meetings would continue on Tuesday as planned.
“The work of the ministers obviously goes on. This is a very sad day for the people of Toronto and the people of Canada,” she said.
City Mayor John Tory urged residents to remain calm.
“This kind of tragic incident is not representative of how we live or who we are or anything to do with life in the city on a day-to-day basis,” he said.
The White House issued a statement saying the US “stands with the Canadian people” and offering “any support Canada may need”.