Muslim family of four killed in 'premeditated' Canada truck
A 20-year-old suspect wearing a vest "like body armor" fled the scene and was arrested at a mall seven kilometers (four miles) from the intersection in London, Ontario where it happened.
"There is evidence that this was a planned, premeditated act, motivated by hate. It is believed that these victims were targeted because they were Muslim," Detective Superintendent Paul Waight told a news conference.
The names of the victims were not released, but they include a 74-year-old woman, a 46-year-old man, a 44-year-old woman and a 15-year-old girl - together representing three generations of the same family, London mayor Ed Holder said.
A nine-year-old boy was also hospitalised following the attack and is recovering.
"Let me be clear, this was an act of mass murder perpetrated against Muslims, against Londoners, rooted in unspeakable hatred," said Holder.
Named as Nathaniel Veltman, the suspect has been charged with four counts of first degree murder and one count of attempted murder.
At about 8:40 pm on Sunday (0040 GMT Monday), according to police, the five family members were walking together along a sidewalk when a black pick-up truck "mounted the curb and struck" them as they waited to cross the intersection.
Waight offered few details of the investigation, but noted that the suspect's social media postings were reviewed by police.
He said local authorities are liaising with federal police and the attorney general about adding "possible terrorism charges."