The driver who was behind the wheel of a semi-truck that caused a pileup on the Coquihalla Highway and sent seven people to hospital is under investigation.

The truck, which belongs to Farid Transport, hit 13 vehicles and missed many more.

“He was swerving in and out, he missed the runaway lane. And he just kept hitting cars,” said witness Jessica Balen. “He was smoking. His brakes smelled bad.”

Witnesses said it appeared as though like the truck lost its brakes on Friday just outside Hope and plowed into traffic ahead.

“He came flying down the hill behind me. Smoke flying off his brakes. He couldn't stop, couldn't slow down,” said witness Chris Bremer.

Hundreds of commuters stuck behind the crash were left waiting for nearly eight hours as emergency vehicles made their way to the scene of the crash.

RCMP said the truck was unable to stop, but did not confirm whether there was a problem with the brakes. The truck is being inspected by the Ministry of Transportation.

“We are certainly investigating what the commercial driver did when he went through the brake check,” said Cpl. Kurt Rosenberg. “The information we have is that he did go through the brake check…but we're investigating exactly what transpired at that brake check.”

Provincial inspectors removed a black box from the truck before it was impounded. CTV News obtained video of the truck showing the damage it sustained.

On Monday investigators will conduct a full mechanical check of the truck and deliver their report to the RCMP. Officers are speaking with the truck's driver, witnesses and injured patients.

By Saturday evening six of the seven people sent to hospital had been released, RCMP said. Most had suffered minor injuries.

With a report from CTV Vancouver’s Sarah MacDonald