Officials at a prison in San Diego County are investigating a video that has gone viral: A group of inmates – some holding cellphones – filmed their own version of the “Mannequin Challenge."

On Nov. 13, a YouTube user dubbed “tben916” posted a video on YouTube titled “Mannequin Challenge: Prison,” which shows inmates at the Richard J. Donovan Correctional Facility (RJDCF) in Otay Mesa, California, taking part in the viral video trend where people hold still – as if they were frozen in time – while a moving camera films the scene.

The one-minute clip starts with inmates holding still in the bathroom, including one sitting on the toilet. It is unclear who is recording, but the camera then moves into what appears to be living quarters, showing an inmate holding a cellphone, a fake fight scene and an inmate reading. The video ends with another inmate in his bunk, also holding a cellphone.

On Thursday night, Terry Thornton with the California Department of Corrections and Rehabilitation, confirmed that the footage had been shot inside the RJDCF. She said officials at the prison are still investigating the incident, including how inmates obtained cellphones, which are not allowed in prison.

The RJDCF is located at 480 Alta Rd. The Warden is Daniel Palermo, who has worked there since 2006.