A clash between two groups of prisoners sparked a riot in Faizabad divisional jail where at least eight inmates were held hostage and assaulted during the stand-off that lasted six hours on Saturday, according to police sources. The inmates threatened to blow up cooking gas cylinders which they took from the jail kitchen and threw stones at the security personnel as reinforcements were rushed in to restore order.Probe ordered Faizabad District Magistrate Anil Kumar Pathak said that a magisterial enquiry has been ordered into the incident. The trouble started at 9 a.m. when a jail functionary complained to the Superintendent about some undertrial prisoners talking on mobile phone, the police said. Miffed with his action, a group of prisoners thrashed him. When some other prisoners objected to it , the group attacked them too and held them hostage. The rioters also broke CCTV cameras installed in jail as chaos reigned. Additional forces were called in, which used drone cameras to take stock of the situation, they said. After more than six hours, the security forces were able to free the eight badly injured hostages who were shifted to Faizabad district hospital, they said. According to sources, the jail has a capacity of 4,000 inmates but over 8,000 prisoners are lodged there.