COLOMBO, Sri Lanka (AP) — Clashes broke out inside a prison in the outskirts of Sri Lanka’s capital, killing at least 25 people and injuring more than 100, officials and a TV station reported Monday.

Police said the unrest at the prison in Negombo, about 35 kilometers (22 miles) north of the capital, Colombo, began on Sunday and continued on Monday. Spokesman Chandana Herath said there were fatalities but could not immediately confirm the toll reported by local television station Hiru.

Victims include both inmates and prison officials, the TV reported.

The reason for the clash was not immediately known.

An official at the area's main state-run hospital said more than 100 people were admitted with injuries from the prison clash. He spoke on condition of anonymity because he was not authorized to speak to the media. He did not specify the injuries.

Sri Lankan prisons are highly congested, with more than 39,000 inmates crowded into a system with a total capacity of just 10,000.