A government travel alert was issued for British travellers to Toronto last night after ten people were killed and 15 injured as a van careered into pedestrians.
City police chief Mark Saunders told a news conference that the incident appeared to be deliberate but the motive was still unknown.
Suspect Alek Minassian, 25, from the Toronto suburb of Richmond Hill, was not previously known to police.
Van rental firm Ryder System confirmed that one of its vehicles was involved and said it was co-operating with authorities.
The incident occurred at Yonge Street and Finch Avenue at 1.30pm local time on Monday. The crime scene encompassed a 1.24 mile stretch of Yonge Street.
Foreign ministers of the G7 leading industrialised nations – Canada, the US, Britain, France, Germany, Italy and Japan – were holding meetings about 18 miles away in the city centre.
In revised travel advice for Canada, the Foreign and Commonwealth Office said: “In an incident in Toronto on 23 April a vehicle struck a number of pedestrians near Yonge and Finch.
“Local authorities have confirmed that they are dealing with a number of casualties, and an investigation is ongoing.
“The area surrounding the incident has been sealed off, and disruption to local transport services can be expected.
“Please follow the advice of the local authorities.”
The FCO added that terrorists are likely to try to carry out attacks in Canada.
The van attack comes just days before British Airways starts its first service to Toronto from Gatwick on May 1.