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.

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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.

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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.

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