Two Secret Service vehicles used by Vice President Joe Biden allegedly struck and killed a pedestrian at an intersection on Washington, DC's Suitland Parkway in the early morning hours of Wednesday, news reports say.

The vice president was not in either of the vehicles when the motorcade, on its way from Andrews Air Force Base to a garage on Washington, struck a pedestrian. A Washington Post traffic report states the accident took place at around 3 a.m. ET near the corner of Naylor Road, on the DC-Maryland border, but other sources place the accident closer to 2:30 a.m. ET.

The pedestrian was taken to St. George's Hospital with "multiple critical injuries" and declared dead later that morning, reports The Hill:

The circumstances of the accident, such as the color of the traffic light and the speed of the vehicles, were unclear but the Park Police was investigating.

Secret Service spokesman Malcolm Wiley said the employees involved in the accident remained at the scene and administered first aid to the man until an ambulance arrived to take him to the hospital.

US Park Police are investigating the accident. As of Wednesday afternoon, they had not released the victim's name.

The Gazette in Gaithersburg, Maryland, reports that two Secret Service agents were the only occupants of the vehicles at the time.

The two vehicles had been flown back to Washington, DC, from Tacoma, Washington, where they were used to transport the vice president to and from a speaking engagement. They were headed to a Secret Service garage at the time of the accident.

The vehicles will remain in Park Police custody during the investigation, which is expected to take about a week.