WASHINGTON (WDVM) — The Metropolitan Police Department (MPD) says a library police officer died Thursday afternoon after a retired police lieutenant shot her in the Anacostia Library.

According to MPD, the retired lieutenant was conducting training at the library, located at 1800 Good Hope Road SE. At the end of the training, the retired lieutenant fired a gun.

The bullet hit the library police officer. Medics took her to the hospital where she died.

Other library police officers, as well as the retired lieutenant, were being interviewed late Thursday afternoon.

The department says it’s working with its partners at the U.S. Attorney’s Office for the District of Columbia in the investigation into exactly what happened.