New Delhi, July 7 -- Clashes broke out inside a prison in the outskirts of Sri Lanka's capital, killing at least 25 people, most of them inmates, and injuring more than 100, officials said Monday.

The unrest at the prison in Negombo, about 35 kilometers (22 miles) north of the capital, Colombo, started among inmates on Sunday, and when guards attempted to intervene on Monday, "they (inmates) started attacking the prison officials," prison spokesman A.C. Gajanayake said.

He told reporters that some inmates attempted to escape but were stopped.

An official at the main state-run hospital in the area said seven prison officials and 18 inmates had died while another 43 were being treated for injuries. He spoke on condition of anonymity beca...