WATERTOWN (CBS) – A tow truck driver was stabbed five times after police said he struck and killed a woman walking in Watertown Square.

And the man accused of stabbing the driver is believed to be the son of the pedestrian who was struck and killed, according to witnesses.

He was arrested and taken to an area hospital. Police have not released the names of anyone involved.

Middlesex District Attorney Marian Ryan said the incident happened around 11:20 a.m. in the busy area of Watertown and Galen streets.

Ryan said a woman in her late 60s was hit and killed by a flatbed tow truck. She died at the scene of the crash.

The tow truck driver was stabbed five times in the torso. He was rushed to the hospital in critical condition.

Witnesses say the woman who was struck and killed had been pinned underneath the tow truck. That’s when a man believed to be her son allegedly went after the tow truck driver and began stabbing him.

“And then, he jumped in the truck, the cabin, and started stabbing and stabbing and stabbing him,” said Zeidan Taha, who called 911 from the scene. “And the driver, you know, opened the door and threw him to the floor. And then the driver went down, and then he kept chasing him, chasing him, and stabbing him, stabbing him.”

The tow truck driver fell down.

“I called the police. I tell them, ‘Hurry up, there’s somebody stabbing somebody,'” Taha said.

Traffic was impacted for several hours in the area of Watertown Square as police continue to investigate the incident.

Watertown Police Chief Mike Lawn said the crime scene was hard to look at for both investigators and the general public.

“This was a bad scene over here for both the people and the public and for our officers,” Lawn said.