LOS ANGELES (AP) — A woman died in custody Tuesday morning at a Los Angeles police station, authorities said.

It was not immediately clear why the woman had been arrested or how long she had been in custody at the 77th Street station south of downtown. Her name was not released.

Police Officer Rosario Cervantes said the woman had complained of pain. She was believed to be about 50 years old.

Officials reported that the woman was unresponsive in the station's jail basement shortly before 6:30 a.m., said Nicholas Prange, a spokesman for the Los Angeles Fire Department.

She was later pronounced dead at the station, Cervantes said.

The Office of the Inspector General is investigating the death.