CLINTON, Md. — A dog followed a group of children onto a school bus Wednesday and attacked four students on board, injuring them, according to Prince George's County police.

The students, who attend Fort Washington Forest Elementary School, were transported to a hospital for treatment, The Washington Post reports. According to Briant Coleman, spokesman for Prince George's County Schools, three of the students have since been released from the hospital.

Coleman said one of the students was bitten and scratched, while two others were just scratched. He was still seeking details on the fourth student's condition. Coleman also said that the bus driver had fought off the dog inside the bus, preventing further injuries to students.

Corp. Clinton Copeland, a spokesman for the Prince George's police department, told The Washington Post that the students did not seem to have provoked the dog. He also said that an officer attempted to restrain the dog once it was off the bus, but it continued to act aggressively, so the officer shot it.