About 40 police officers were injured trying to break up a five-hour riot by Protestant militants who burned 10 cars and a double-decker bus in Belfast (search), officials said Friday.

Police said the rioters threw scores of gasoline bombs and at least one homemade grenade and tried to drive one hijacked vehicle into police lines late Thursday. Heavily armored police in flame-retardant suits suffered a range of injuries, none life-threatening.

Officers fired 11 baton rounds, or "plastic bullets," in response. No civilians were reported injured, although it is typical for people lightly injured while rioting to avoid hospitals for fear of being arrested.

"We faced a very violent situation that was life-threatening at times. ... We had so many petrol bombs thrown at our lines, we stopped counting," said Assistant Chief Constable Wesley Wilson (search), who commanded the police operation.

A spokeswoman for the Police Service of Northern Ireland, who declined to be named because she is a civil servant, said 40 police officers were injured.

The mob, which dispersed from Belfast's Crumlin Road and Shankill Road areas around 1 a.m. Friday, claimed to be venting their anger over recent police raids on the homes of Protestant paramilitary figures in the area. About 15 homes were raided and six men arrested shortly before the riot began.

Wilson said the rioters appeared to have been influenced by members of an outlawed Protestant gang, the Ulster Volunteer Force, which is waging a deadly feud with another gang, the Loyalist Volunteer Force (search). The UVF has been blamed for killing three Protestant men in the past month in north Belfast. Police have raided more than a dozen homes of UVF members in the area.

"Our operations are trying to stop the feud between the UVF and LVF, so it's reasonable to suspect that the UVF had a hand in orchestrating this (riot)," Wilson said.

Wilson rejected allegations that police have been heavy-handed during searches. He said his officers had been verbally and physically attacked while searching militants' homes, including one officer who was hit in the head with a brick.

Wilson said no rioters were arrested Thursday night, but police armored cars with video cameras mounted in protective cages on their roofs had filmed rioters and a team of detectives was pouring over the footage Friday.