RICHMOND (CBS SF) — A tanker truck rolled over on the Richmond-San Rafael Bridge this evening, according to the California Highway Patrol.

The crash was reported on eastbound Interstate Highway 580 around 6:55 p.m. when a big rig with an empty tank trailer hit a concrete railing and overturned blocking the shoulder and the slow lane.

A Sig-alert was issued at 7:13 p.m.

The fast lane has been closing intermittently as crews work to clear the roadway, according to the CHP.

As of 9:45 p.m. the slow lane was expected to remain closed for several hours.