WASHINGTON, Nov. 11 (UPI) — Vehicles used to transport U.S. Vice President Joe Biden were involved in a fatal accident Wednesday, a federal official said.

Two Secret Service employees were driving the armored sports utility vehicle and limousine in Temple Hill, Md., when they struck and killed a man at an intersection, Sgt. David Schlosser of the U.S. Park Police said.

Biden wasn’t in either vehicle when the crash occurred, The Hill reported.

Following Secret Service policy, the vehicles had been flown to Fort Lewis, Wash., on a military aircraft for Biden’s trip there Tuesday and were being returned to a secure storage facility at an Air Force base in Maryland Wednesday.

Circumstances surrounding the accident, such as the color of the traffic light and the vehicles’ speed, were unclear but the Park Police was investigating, Schlosser said.

Secret Service spokesman Malcolm Wiley said the employees involved stayed at the accident scene and administered first aid to the victim until emergency medical personnel arrived.