"Investigators believe that this was an intentional act and that the victims were targeted due to their Islamic faith", a statement from police in London, Ontario, said on Monday.
Police believe the collision was a planned hate crime.
Emergency crews responded at 8:40 p.m. Sunday to reports of a vehicle striking pedestrians at Hyde Park and South Carriage roads, where one woman was pronounced dead at the scene, police said.
A 20-year-old suspect was arrested by the police in Canada.
Police Chief Steve Williams said one adult female who was struck died at the scene, while an adult male, adult female, and two children were rushed to hospital by paramedics.
"He was a family guy, very much involved in the community, a regular member of our mosque, a really, really great father", the neighbor, who was not identified, said of Syed Afzaal. A nine-year-old boy was reported in serious condition.
A 20-year-old Canadian man has been charged with four counts of murder and one count of attempted murder.
Police are weighing possible terrorism charges, he said. Islamophobia has no place in any of our communities.
Canada is generally welcoming toward immigrants and all religions, but in 2017 a French Canadian man known for far-right, nationalist views went on a shooting rampage at a Quebec City mosque that killed six people.
The leader of the federal New Democrats says the killing of a Muslim family in London, Ont., is "an act of Islamophobia & terror". Police said a black pickup truck mounted a curb and struck the victims at an intersection.
London Mayor Ed Holder called the attack "an act of mass murder perpetuated against Muslims", per AP.
"Words fail on a day as dark as this but still, words matter", said Holder. "Not tomorrow. Today. For the sake of our children, our families, our communities".
"Hate can not win, and every person in Canada must feel safe in their identity", she said.
"I'm still in shock", said Martin visibily emotional.
From her apartment, Martin said she could see the scene and watched an official drape a sheet over one body about midnight.
Zahid Khan, a family friend, said the three generations among the dead were a grandmother, father, mother and teenage daughter.
Blue evidence markers on the ground dotted the intersection and officers were performing line searches for several hundred metres in the field next to the sidewalk.
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