A van which hit pedestrians in Toronto swerved across four lanes to hit passers-by "deliberately", according to Sky News.
Ten people died and 15 were injured, some critically, police in Canada have confirmed.
The driver of the van, Alek Minassian, 25, has been arrested.
Toronto's police chief Mark Saunders said the motive is not yet known and the suspect was not on police files.
Witnesses have told Sky News the van was "fairly deliberately" hitting pedestrians and that the collision looked like it was "on purpose".
Henry Miller, who works from home for a bank in Toronto and lives in an apartment overlooking the street, said: "I heard a large amount of honking... and I stepped out on to the balcony to see what was causing the trouble and at this point I saw a lady lying on the floor and the van driving off with people running around trying to help her."