Muni bus involved in crash on Bay Bridge causing major backup

Vehicles are bumper to bumper on the westbound lanes of the Bay Bridge Tuesday night after a Muni bus was involved in a collision with a vehicle and the vehicle rolled over, officials say. 

The crash happened at around 9:30 p.m. as it was first reported to California Highway Patrol near the Yerba Buena Island Tunnel. 

A number 25 Muni bus was at the scene of the crash. This is the bus that serves Treasure Island

Four lanes of traffic were initially blocked, before conditions slightly improved to two lanes being blocked. By 10:38 all lanes reopened, but at one point, the backup extended to near the toll plaza. 

There were no confirmed injuries. 

This is a developing news story.