A passenger bus carrying more than two dozen passengers overturned on a San Francisco highway Friday night.

The crash was reported just after 8 p.m. on southbound U.S. Highway 101 near the Cesar Chavez Street off-ramp, according to the California Highway Patrol.

Shortly after, the CHP issued a Sig-alert and estimated that at least two lanes of the highway would remain closed for up to four hours.

Emergency personnel said there were about 30 passengers on the bus, and at least one was suffering from major injuries.

Further details were not immediately available.