A school bus collided with a passenger vehicle in the Aspen Hill section of Montgomery County on Friday morning, injuring five adults, authorities said.

The crash happened about 7:45 a.m. at Georgia Avenue and Heathfield Road, according to officials.

There were only a handful of children aboard the bus at the time of the wreck, according to a spokeswoman for the county’s fire and rescue service. None of the children was injured, she said.

Four adults suffered relatively minor injuries and were taken to area hospitals. Among the four were the bus driver and an aide, according to initial information from the scene, the spokeswoman said.

Another adult sustained more serious injuries, but the injuries were not considered life-threatening, the spokeswoman said.

The crash is under investigation.