Authorities in Virginia are still searching for four inmates who escaped from a federal prison satellite camp over the weekend.

The inmates were discovered missing around 1:45 a.m. EST Saturday, according to a news release from the Federal Bureau of Prisons (BOP). Although details about how the inmates were able to escape prison were not revealed, the BOP called it a “walkaway.”

Inmates Corey Branch, Tavares Lajuane Graham, Kareem Allen Shaw, and Lamonte Rashawn Willis escaped from the Petersburg Federal Correctional Complex satellite camp in Hopewell, Virginia, about 50 miles south of Richmond.

Officials described the satellite camp as a minimum security facility that houses 185 male inmates. Branch, 41, was sentenced to over 13 years for a convicted felon in possession of a firearm and possession with intent to distribute fentanyl.

Graham, 44, was serving a 10-year sentence for possession with intent to distribute 500 grams or more of cocaine and 28 grams or more of cocaine base, and possession of a firearm in furtherance of a drug trafficking crime, according to the BOP.

Shaw, 46, was sentenced to more than 16 years for conspiracy to possess with intent to distribute a measurable quantity of heroin. Willis, 30, was serving a 16-year sentence for possessing and concealing a stolen firearm and possession of a firearm by a convicted felon.

Following the inmates’ prison break, officials notified the FBI, U.S. Marshals Service, and other law enforcement agencies. An internal investigation has also been launched into the matter and the search for the four inmates continues.

Investigators advise anyone with information on the escaped inmates to contact the U.S. Marshals Service.

Indiana's Federal Correctional Complex Terre Haute where Dustin Higgs was due to become the 13th federal inmate put to death under the Trump administration
Indiana's Federal Correctional Complex Terre Haute where Dustin Higgs was due to become the 13th federal inmate put to death under the Trump administration GETTY IMAGES NORTH AMERICA / SCOTT OLSON