The driver of a tanker truck died Wednesday afternoon when he slammed into another tanker truck stopped in front of him on Highway 37, triggering a chain reaction crash of multiple vehicles east of Lakeville Highway, according to the California Highway Patrol.

The fatal 3:38 p.m. wreck in the eastbound direction caused a massive traffic back-up during the peak of the evening commute. The eastbound lanes were closed for more than six hours with most traffic redirected at Lakeville Highway for extensive detours.

The big rig driver who was killed was in the slow lane, towing a single trailer loaded with what appeared to be vinegar. He plowed into the back of a stopped rig in front of him at an estimated 50 to 60 miles per hour, according to CHP Officer Andrew Barclay.

The crash pushed the stopped rig, which had an empty double trailer, into four other vehicles, but the occupants sustained no injuries, or had only complaints of pain, Barclay said.

The investigation into the fatality and clean up of spilled diesel fuel lasted into the night, with Caltrans crews estimating the road might be closed until midnight. The identity of the male driver was not released, pending notification of family.

Some of the stopped traffic initially was able to get by in the center divider.

“The biggest issue is cars in the center divider trying to look at the crash,” Barclay said from the scene.

Motorists traveling towards Solano County out of Marin were advised to take the Richmond-San Rafael Bridge. Motorists out of Sonoma County were advised to take Highway 116 to Highway 121 and Highway 37.