ARLINGTON, Va. (AP) — Two buses crashed head-on near a Pentagon bus stop on Friday, injuring 23 people, including Defense Department personnel.

The Omni Ride and Fairfax Connector transit buses struck each other shortly before 7:30 a.m., according to a press release from the Pentagon Force Protection Agency. Emergency personnel transported 18 of the injured to local hospitals for further medical evaluation. Five were treated at the scene.

Ten of the 23 injured passengers are from the Defense Department.

The Metro Access Road was closed pending an accident investigation.

The accident altered mass transit operations for several hours. Camera footage from the scene showed the two buses colliding.

The Arlington Fire Department confirmed that the crash occurred and that it responded, but it referred questions to the Pentagon Force Protection Agency, the federal law enforcement agency at the Pentagon.

It was unclear what caused the crash.