A motorist who apparently wasn’t paying attention to the cars in front of him caused a three-car collision that created a significant traffic jam on the Casco Bay Bridge Thursday.

The accident was reported around 4:40 p.m. during the evening commute. The accident took place on the southbound lanes of the bridge that motorists use to cross over the harbor from Portland into South Portland.

Sgt. John Sutton said a driver, who is not being identified, crashed into the rear-end of a car that had stopped for a traffic light near the bridge’s intersection with Broadway and Waterman Drive in South Portland. The impact of that collision sent the vehicle into another stopped car.

There were no serious injuries reported, but traffic on that side of the bridge was delayed for about 30 minutes.

“It happened at a time when a lot of people were trying to get home from work,” Sutton said.