The driver of a pickup truck in London, Ontario, who ran down five pedestrians, killing four of them, chose his victims because they were Muslim, the police said on Monday.

“There is evidence that this was a planned, premeditated act and that the family was targeted because of their Muslim faith,” said Detective Superintendent Paul Waight of the London Police at a news conference.

Mayor Ed Holder of London, which is midway between Detroit and Toronto, called it “an act of mass murder perpetrated against Muslims, against Londoners and rooted in unspeakable hatred.”

The killings happened on one of the first summerlike weekends of the year in London. The police told reporters that a man in a black pickup drove up on a curb and mowed down a family standing on the sidewalk and waiting to cross a busy suburban road.

The victims were identified by the family in a statement as Salman Afzaal, 46; his wife, Madiha, 44; their 15-year-old daughter, Yumna; and Mr. Afzaal’s 74-year-old mother. The statement said that their 9-year-old son, Fayed, remained in hospital “on the road to recovery from serious injury.”

“Everyone who knew Salman and the rest of the Afzaal family know the model family they were as Muslims, Canadians and Pakistanis,” the statement added.

The driver sped away at a high speed, running through several red lights before being stopped and arrested in a shopping mall parking lot a little more than four miles away. The police said he was wearing body armor at the time.

The suspected attacker was publicly identified as Nathaniel Veltman, 20, on Monday, when he was charged with four counts of first-degree, or premeditated, murder and one count of attempted murder. The police said that they were consulting the attorney general and the Royal Canadian Mounted Police about possible terrorism charges.