WILLOWS, Calif. -

An accident that injured a Willows CHP officer was caught on dash cam and he says it could have been avoided had the at-fault driver followed the law and been rested behind the wheel.

Officer Joseph Stokes was on patrol shortly after 1:00 a.m. Wednesday, Feb. 26, when he pulled a man driving a Hyundai Elantra over for speeding.

In the video you can see Stokes on the passenger side of the Elantra talking to the man inside.

Then, out of nowhere, a truck towing a trailer rushes by, the trailer clipping the Elantra, sending it hopping into Stokes.

Stokes stumbles backward, down an embankment and disappears from view.

His partner rushes in to help and Stokes re-emerges before the adrenaline coursing through him subsides.

“That's when I went to my knees, it just overwhelmed me right there. Some of it was the injury, some of it was -- I was real lucky because it could have been worse," he said.

Stokes falls to his knees, suffering from back spasms and a bruised hip.

His partner and, ironically, the man he stopped, came to his aid.

“That was sort of remarkable, especially if you see him jumping out the window, you know and checking for me," Stokes said. "That's a nice guy. One of the type of people we want to meet out there.”

Fortunately, Stokes followed protocol and approached the right side of the man's vehicle.

“If I had been on the left side, basically we all at the office agreed that, you know, I'd be critical or dead. The trailer just would have ran me over,” he said.

The man who caused the accident eventually stopped less than a mile away and was later found to be at fault for the crash.

Stokes says there's a lesson to learn from his mistake.

“State law requires people to move over or slow down below the speed limit when they're approaching emergency vehicles, and that's something that he failed to do,” Stokes said.

But what about the man he stopped for speeding, the man that would eventually come to his aid?

“He did not get a ticket or anything like that. We called AAA, got his tire changed. Other than that he was sent on his way.”

Today Stokes is mostly healthy, with only some recurring pain.

He says the man who caused the accident was in the middle of a long trip when it happened and that tired drivers are frequently to blame for accidents like these.

He urges people to stay rested and please slow down when they see emergency vehicles.

Also, he says people need to pull over when they see emergency light because it's the law.