A van plowed into eight to 10 people in a busy intersection in Toronto on Monday afternoon, police said.

The driver of the van has been taken into custody, according to police. Authorities did not immediately identify the driver.

"We do not know the cause or reason for the collision but we can confirm the van has been located and the driver is in custody," a Toronto police spokeswoman told NBC News.

Police said they would not comment on the number injured or the severity of their injuries at this point. Graphic images from the scene showed at least two people on the ground near what appeared to be blood.

An eyewitness, Diego DeMatos, told NBC News that he saw several pedestrians on the ground, surrounded by crowds of "screaming and crying" people.

"The driver was swerving back and forth between the sidewalk and the road," said DeMatos, 23. "I saw where the van hit two people and then kept going."

Another witness, Phil Zullo, told Canadian Press that he had seen police officers arresting a man who had been driving a Ruder rental truck and had witnessed people "strewn all over the road."

"I must have seen about five, six people being resuscitated by bystanders and by ambulance drivers," Zullo told the news agency. "It was awful. Brutal."

Prime Minister Justin Trudeau conveyed his sympathies for the injured.

"Our hearts go out to anyone affected," Trudeau said in Ottawa. "We are going to have more to learn and more to say in the coming hours."

Toronto's mayor, John Tory, confirmed that here had been a "very tragic incident" at the intersection of Yonge Street and Finch Avenue. He also expressed his sympathy for the victims and first responders.

This is a developing story.