Six people, including four Prince George's County firefighters, were injured in a pair of crashes on the Capital Beltway.
The second crash involved a fire truck that was rear-ended as it provided barrier protection for emergency workers responding to the initial crash.
All four firefighters were treated and released from the hospital Saturday.
The accidents occurred on the beltway's inner loop near Allentown Road in Forestville about 3:30 a.m. Saturday. The inner loop was closed for several hours as a result.
Maryland State Police say the initial crash occurred when a driver fell asleep and hit an unattended car on the side of the highway.
After the fire truck arrived police say another motorist, later determined to be under the influence of alcohol, crashed into the firetruck.