British police have begun raiding houses in London on Thursday in connection with the riots that have gripped the country for much of the past week.

Deputy Assistant Commissioner Steve Kavanagh says that officers began knocking on doors to arrest people across the city in the early hours of Thursday. He says more than 100 arrest warrants will be served in the “coming hours and days.”

Later Thursday, British Prime Minister David Cameron will address an emergency session of parliament on the riots, which largely subsided on Wednesday night.

Mr. Cameron has faced criticism over his plan to reduce the police budget by 20 percent. On Wednesday, London Mayor Boris Johnson criticized the proposed cuts, saying the riots do not allow for “substantial cuts” in police numbers. Mr. Cameron has said that the cuts will not “reduce the amount of visible policing.”

Britain had its first calm night Wednesday after four straight nights of riots. Police and witnesses report just minor incidents as thousands of riot police fill the streets of London, Manchester, Liverpool, and Birmingham.

Police have arrested more than 1,100 people since the riots began on Saturday. The violence was touched off by the police shooting death last week of a 29-year-old man in London's economically depressed Tottenham neighborhood.

Prime Minister Cameron has already called thousands of additional police onto the streets and authorized the use of water cannons, saying a “fightback” is under way to restore law and order.

Hundreds of youths — many saying they are sick of unemployment and cuts in government help — have burned buildings and cars, looted stores, smashed windows, and attacked police.

Birmingham police opened a murder investigation Wednesday when three men were run over by a car and killed apparently while trying to protect their neighborhood from looters. Police have a suspect in custody.