LOS ANGELES — The teenage driver of a BMW who ran a red light in the neighborhood of Boyle Heights on Monday, fatally striking a pedestrian and then crashing into the back of a school bus, is being investigated for being under the influence of drugs or alcohol during the incident. The two teenage passengers who were in the car are also under investigation.

California Highway Patrol officer John Harris told the Los Angeles Times that the teens fled the scene on foot after crashing into the bus. Two of the boys were grabbed by nearby construction workers while the third was arrested when he turned up at a hospital with injuries from the collision.

According to law enforcement sources, the boys in the car may have been using narcotics or sniffing glue before the collision. Blood samples were taken from the suspects to determine if they had been using drugs or alcohol, the Los Angeles Times reports.

A manslaughter charge is likely to be pursued against the driver if he is found to have been under the influence.

Fifty students were on the overturned bus. Eighteen students were taken to the hospital and treated for minor injuries. The bus driver remained in the hospital in fair condition on Tuesday morning and at least three students were still in the hospital with minor injuries, KABC reports.

School counselors and Los Angeles Mayor Antonio Villaraigosa rode the bus with the students on Tuesday to send the message that it's still safe to take the bus to school.

"They may be feeling anxiety, anger, some manifestation of trauma, and that's normal in situations like this," Villaraigosa told the news source.