Officer Jelani Prather of the Metropolitan Police Department's Fifth District was off-duty at the time of the accident. He was driving along Intersate 270 just south of the Falls Road exit a little before 1 p.m.
For reasons unknown, he swerved into the right shoulder, striking a tanker truck that was parked on the side of the road.
Driver Antonio Donnell Lucas had stopped to check out a mechanical problem on the tanker when he saw a Scion car enter the shoulder and head towards the truck.
He honked and put the truck in gear to try to move out of the way, but the car ran into the back of the truck. Both vehicles slid for 75 feet before coming to a stop.
It is unknown why Prather veered off the road and into the truck. Investigators said the absence of skid marks lead them to believe that Prather did not brake before the accident. Witnesses at the scene also said the car didn't appear to brake or swerve to avoid the crash.
The accident is still under investigation, and no charges have been filed.
Commander Andrew Solberg of the Metropolitan Police Department said Prather had been with the department for 10 years. He was assigned to a motorcycle beat in the Fifth District in northeast Washington.