(CNN) -- Fifty-five police officers were injured in clashes that marked a controversial holiday march in Northern Ireland, authorities said Tuesday.
One officer, a female, remained hospitalized in stable condition, police said in a statement. Police said Monday she had been struck in the head by an object thrown at her.
Police Service of Northern Ireland Chief Constable Matt Baggott condemned the disorder in the Ardoyne area of Belfast, the statement said.
"A number of my colleagues have been injured and I wish them a speedy recovery," he said. "It places a great burden on my colleagues who exercised superb restraint, superb professionalism and superb courage. Last night we had people working for 24, 36, 48 hours and I would like to take this opportunity to thank them all."
The violence began on the eve of July 12, known as "The Twelfth" by Protestants who march to celebrate the victory of England's King William III over his ousted Catholic predecessor James II in 1689. The holiday has previously been marred by violence, and has been a source of tension between Catholics and Protestants.
More than 100 riot police removed Catholic protesters from a road in north Belfast to allow the march to take place, said journalist Peter Taggart. Rioters pelted police with Molotov cocktails and other explosives, and officers fired baton rounds and used water cannons in attempts to break up the crowds, police said. Several vehicles were carjacked and set ablaze, police said.
"The cost of policing last night in that small part of Northern Ireland is the equivalent of a ward in a hospital," Baggott said in the police statement. "It's the equivalent of a primary school. It's the equivalent of neighborhood policing. It is time to have that big debate about what is really important for the future in Northern Ireland."
"I would like to see a very loud collective voice making sure that these people are condemned," he said. "Everyone who has a say in the future of Northern Ireland must condemn those responsible and make sure it is clear to them that they have no place in that future."
He said authorities will launch "a major investigation" into the violence and appealed for help from the public.