Two D.C. Police officers and two others were seriously injured in a car crash on the Anacostia Freeway this afternoon.

The MPD officers were struck while stopping to help the driver of a disabled vehicle, according to tweets from Mayor Muriel Bowser and confirmed by MPD Chief Peter Newsham in a news conference at MedStar Washington Hospital Center, where the two officers are in serious condition.

The other two victims are the person in the striking vehicle and the person in the disabled vehicle, Newsham said. One was transported by ground to MedStar with serious injuries, and the other transported by ground to George Washington Hospital with serious, but non-life threatening, injuries, according to Doug Buchanan of D.C. Fire and EMS.

“We don’t know what caused the other vehicle to lose control,” said Newsham, whose first day as interim chief was last Thursday.

He emphasized that, even though the disabled car was not in their district, “this is the type of thing police officers do on a daily basis—they get out of their cars to assist people on dangerous roadways all the time, and we’re very proud of the fact that they did that.”

They were airlifted to the hospital after the 911 call came in at 1:03, according to D.C Fire and EMS.