A school bus driver will be charged with endangering a 10-year-old boy for intentionally braking suddenly so the boy would fall down, police said.

The bus driver was upset because the boy would not remain in his seat, Harmony Township police Sgt. Jim Essek said.

The driver told the boy to stop moving around before allegedly threatening him by saying, "If you do it again, I'll knock you down," Essek said.

When the fourth-grader got up again, the bus driver hit the brakes.

The incident happened Tuesday in the Ambridge Area School District, about 25 miles northwest of Pittsburgh.

Police Chief Jack Lively said police will not release the driver's identity until charges are filed, likely by Monday.

Investigators have seized a surveillance video from the bus. The boy dropped to the floor out of camera view, but is seen getting up holding his face. Other students are knocked around and one is flipped over a seat.

The driver and the boy have had run-ins before, parents said.

The boy's mother claimed he was "singled out" for discipline when students got rowdy in the past and asked school officials to have someone monitor the bus.

Lively said the monitor was on the bus Tuesday, but didn't get out of his seat to intervene.

School officials said they are reviewing the incident.