The death toll from a riot at a Salvadoran prison rose to 21 after authorities on Sunday reported an additional fatality.

Prisons director Roberto Villanova said the maximum-security prison in Apanteos, 40 miles west of the capital San Salvador, will be under a state of emergency for 15 days. Police and soldiers have kept the prison surrounded since Saturday and all visits were suspended. Worried family members gathered outside, hoping for information.

Alberto Uribe, a spokesman for the country's prison system, said officials had searched the entire prison and found 21 dead inmates, one more than was reported Saturday.

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The riot began late Friday when members of the Mara 18 gang seized a guard and refused to enter their cell block at the prison. They then began tearing down the prison's flimsy interior walls to reach other inmates.

Deputy police director Jose Tobar told El Diario de Hoy newspaper that the gang members appeared to have planned the riot to kill certain prisoners.

Guards fled the prison and a battle raged between hundreds of inmates armed with shovels and other makeshift weapons.

Officials regained control of the prison Saturday, sending in more than 2,000 police, soldiers and security guards. More than 200 prisoners were transferred to other jails. Villanova said more prisoners will be transferred to avoid another uprising.

Built to hold 1,800 inmates, the prison houses more than 3,000.

Central American penitentiaries have long struggled with overcrowding, fueled in part by a regional crackdown on gangs that has filled prisons with rival groups.

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