DENVER — Denver police are investigating a report that a high school student was subjected to racial slurs and physically assaulted on a mass-transit bus.

Denver Public Schools said Friday the student was black and the alleged attacker was an older white man, and that the assault appeared to be racially motivated.

Police spokesman John White said he couldn’t confirm whether race was a factor. He said officers are looking for witnesses and reviewing video from a camera on the bus.

The school district says in a written report the incident occurred Wednesday.

The district says witnesses reported the man singled out the student because of the student’s race. The district says other passengers intervened and the man got off the bus.

The statement says the student returned to school the next day.