Authorities say a school bus plunged off a highway overpass in Houston after being hit by a car on Tuesday, killing two teenage students and seriously injuring three other people.

The Houston Independent School District says a 17-year-old female student died at the scene, while a 14-year-old girl died at a hospital.

The driver and the other passengers on the bus — two male students — are hospitalized.

Police spokesman Victor Senties said investigators believe that a car struck the front driver's side of the bus after swerving to avoid another vehicle during morning rush-hour traffic.

The bus then lurched to the right, struck a guardrail and toppled to the road below.

Police say the accident remains under investigation.