Three inmates have been killed and 14 wounded in a riot at the Philippines' national penitentiary, officials say.
The brawl at the New Bilibid Prison in the Manila suburban city of Muntinlupa broke out on Sunday and lasted for almost an hour, Bureau of Corrections spokesperson Gabriel Chaclag said on Monday.
"The violence started from verbal heckling with adjacent dormintories... until a gunshot was heard," he said.
"That lead to an exchange of gunshots and chaos erupted. Everyone was on self-defence mode."
Chaclag said seven detainees who started the violence were identified and taken to an isolation area while authorities decide on disciplinary action.
Prison guards seized improvised pistols and bladed weapons from the inmates, he added.
The New Bilibid Prison has 18,000 inmates. Closed circuit TV cameras are installed at the facility, but only in strategic areas. Prison guards do not monitor inmates 24 hours.