A driver ploughed his white Ryder rental van into a crowd, killing nine people and injuring 16 along a roughly mile-long stretch of busy Toronto sidewalk during lunch hour on a sunny Monday afternoon, police said.

Officials declined to answer questions about what motivated the driver to steer his vehicle toward people just before 1:30 p.m. (1730 GMT). They said the driver was in custody and stopped short of calling it a deliberate act.

But at least one witness described the driver as appearing to deliberately target victims on his roughly mile-long (1.6 km-long) rampage, according to media reports.

“This is going to be a long investigation,” Toronto Deputy Chief Peter Yuen told a news conference after disclosing the death toll.

A Reuters witness saw at least two tarp-covered bodies at the site of the incident. Five people remained in critical condition at Sunnybrook Health Services Centre on Monday afternoon, the hospital said.

Canada’s public safety minister, Ralph Goodale, declined to comment on what may have motivated the attack.

“The investigation is at a stage where no further information can be confirmed at this point,” Goodale told a news conference said. “The police are conducting obviously their thorough investigation to determine what happened and why it happened, the motivations involved.”

Ryder System Inc (R.N) spokeswoman Claudia Panfil confirmed that one of the company’s rental vehicles had been involved and said the company was cooperating with authorities.

There has been a string of deadly vehicle attacks in the United States and Europe, including an Oct. 31 attack in New York that killed eight. The Islamic State militant group encourages its supporters to use vehicles for attacks.

‘IT’S UNPRECEDENTED’

The incident was one of the most violent in recent Canadian history.

A former Canadian university student pleaded guilty last month to killing six men praying in a Quebec City mosque in January 2017.

In September, a Somali refugee was charged with attempted murder over allegations he ran down four pedestrians with a car and stabbed a police officer outside a sports stadium in Edmonton, Alberta.

“It’s unprecedented,” said John Flengas, acting superintendent of Toronto’s paramedic services. We’ve never seen anything like this in the city of Toronto.”

The incident occurred about 30 km (18 miles) from the site where Toronto is hosting a meeting of Group of Seven foreign ministers from Canada, the United States, Britain, France, Germany, Italy and Japan, but had no noticeable effect on that event’s security.

A man who gave his name as Ali told CNN he saw the van and that the driver appeared to have been targeting people.

“This person was intentionally doing this, he was killing everybody,” the man said. “He kept going, he kept going. People were getting hit, one after another.”

He said a number of the victims were older people and that he saw at one point a stroller fly into the air.

At least one person was struck outside an Anglican church, north of where the van came to rest in front of a condominium tower.

Some of the victims were struck in a public square popular with office workers on lunch breaks. Aerial photos of the scene posted on social media showed a food truck parked just a few feet away from where emergency workers transferred people onto stretchers.