A Greyhound bus flipped on its side on a rainy highway in San Jose killing at least two people and injuring more than a dozen others Tuesday, according to California Highway Patrol.

The bus was carrying 39 passengers and one driver, traveling north on Highway 101 near Highway 85 when it crashed around 6:40 a.m. A passenger told Fox 2 the vehicle had been weaving back and forth before it crashed.

Four people were transported to area hospitals with major to moderate injuries. In addition, a boy of undetermined age was taken to a hospital as a precaution, said California Highway Patrol officer Chris Miceli. San Jose Fire Department Capt. Christopher Salcido said 13 others suffered minor injuries and were treated at the scene.

The bus had left from Los Angeles with planned stops in San Jose, San Francisco and Oakland.

Video from the scene showed the bus on its side, with debris spilled onto the roadway. A motorist traveling south hit some of the debris, damaging the car but leaving the driver uninjured, officials said.

The accident snarled a morning commute already slowed by rain, backing up northbound Highway 101 for several miles.

Investigators did not immediately reveal the cause of the crash.

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The Associated Press contributed to this report.