HOPEWELL, VA. (AP) — Federal officials say four inmates have escaped from a federal prison’s satellite camp in Virginia.

The Federal Bureau of Prisons says inmates Corey Branch, Tavares Lajuane Graham, Lamonte Rashawn Willis and Kareem Allen Shaw were discovered missing from the Federal Correctional Complex Petersburg’s satellite camp in Hopewell, Virginia, around 1:45 a.m. Saturday.

Officials say the minimum security facility houses 185 male offenders, but they did not release any details about how the inmates escaped.

Officials say the U.S. Marshals Service, the FBI and other law enforcement agencies were notified and an internal investigation has been initiated.