COLOMBO (AFP) — Sri Lanka on Tuesday launched an investigation into its deadliest prison riot in years after the death toll from clashes between rival drug gangs at Negombo prison rose to 27.

Justice Minister Harshana Nanayakkara told Parliament that authorities had opened a criminal investigation alongside a government-appointed commission to examine Monday’s violence.

Police said the latest victim, an inmate, died overnight. A preliminary investigation found rival gangs fought inside the prison before overpowering guards, seizing their weapons and opening fire. Nanayakkara said inmates also smashed a CCTV camera during the unrest.0

Doctors said 97 people, including 23 prison officers, remained hospitalized in Negombo with gunshot wounds, cuts and severe bruises. Another 19 inmates were being treated at a hospital in Colombo.

Seven prison guards were killed while trying to stop the violence, a police official told AFP.

“Human beings have died, and there is deep shock over that. This is something that should never have occurred,” Nanayakkara said.

Authorities tightened security around the prison, deploying armed police and commandos to guard the perimeter but not entering the facility. Prison buses were seen transferring inmates to other prisons as officials relocated detainees following the violence.