SAN RAFAEL (CBS SF) — A fire on a school bus traveling on the Richmond San Rafael Bridge Friday afternoon shutdown all westbound lanes on the span for about a half an hour, according to authorities.

CHP first reported the fire on the school bus at about 2:20 p.m. around midspan on the bridge. Smoke and sparks appeared to be coming from the back of the bus, authorities said.

A Sig Alert was issued and fire units from both Richmond and San Rafael responded. The fire was put out shortly before 3 p.m.

Video shot by Chopper 5 showed that the bus had been moved from midspan towards the San Rafael end of the bridge. Several fire units could be seen near the bus.

There was no word from authorities on any injuries from the fire or whether there were any passengers aboard during the incident.

As of about 3 p.m., CHP reported the right lane remained blocked, though some traffic was slowly making its way past the bus.

CHP Marin posted on its Twitter account that all westbound lanes had reopened as of about 3:45 p.m.