Washington — Tuesday’s clash involving protesters and security guards for visiting Turkish President Recep Tayyip Erdogan prompted outrage by local and U.S. officials who accused the guards of using violence to quell what had been a peaceful demonstration in Northwest Washington.

D.C. police arrested two men, one from Virginia and one from New York, and said they are pursuing charges against additional suspects since the melee outside the Turkish ambassador’s residence. Eleven people were injured, among them a police officer. Some were kicked and stomped, their heads bloodied.

Included in the police search are members of Erdogan’s armed protective detail, according to two people with direct knowledge of the case. Police are working with the U.S. State Department and the U.S. Secret Service to identify people seen on videos and obtain arrest warrants, even as they anticipated thorny issues involving diplomatic immunity or the special status afforded to those who guard visiting heads of state.

House Foreign Affairs Committee Chairman Edward Royce, R-Calif., said “agents of foreign governments should never be immune from prosecution for felonious behavior.” In a letter to Attorney General Jeff Sessions, he urged a quick inquiry and the filing of “appropriate criminal charges” before the security officers leave the country.

In a statement, the State Department said “violence is never an appropriate response to free speech.” It added that the United States is “communicating our concern with the Turkish government in the strongest possible terms.”

D.C. Police Chief Peter Newsham, whose department is leading the investigation, decried the violence. Mayor Muriel Bowser said “police are working very hard with our partners to see if we can get to the bottom of this,” adding that “it was a pretty savage beating.” And Sen. John McCain, R-Ariz., added: “This is the United States of America. We do not do this here. There is no excuse for this kind of thuggish behavior.”

A Turkish state news agency acknowledged that guards for Erdogan, who had earlier met with President Donald Trump at the White House, had targeted demonstrators. Many of the aggressors seen on video were wearing dark suits and ties, and several had guns. At least two of the guns were seen on video being dropped and then picked up during skirmishes.

The Anadolu news agency blamed the incident on an “inadequate” response by police, implying anger over authorities not stopping the protest. The agency framed the guards’ actions as a response to the presence of “terrorist” sympathizers — apparently a reference to Kurdish activists. Demonstrators recounted being kicked, beaten and bloodied while cowering on the ground, and they complained that police did not move quickly to stop the violence.

Representatives from the Turkish Embassy in Washington did not respond to a request for comment.

Tuesday’s melee highlighted the political divisions and conflicts that in some cases have roiled Turkey for decades and have become far more acrimonious and violent of late. After Erdogan’s government survived a coup attempt last summer, authorities have pursued a wide-ranging crackdown on enemies and dissidents. Nearly 200,000 people have been arrested, dismissed or suspended from their jobs.

The government has faced a resurgent threat from militant groups, including the Islamic State and the separatist Kurdistan Workers’ Party, or PKK. In turn, militant attacks and the state’s iron-fisted response, have fed a deepening sense of political polarization in Turkey. A protest leader denied that any of the participants were involved with the PKK or sympathized with the group.

Tuesday’s group was made up of roughly two dozen demonstrators including those angry at Erdogan’s crackdown on dissent and his consolidation of power. Others were Kurdish activists, including supporters of a pro-Kurdish political party in Turkey whose leaders have been prosecuted by the Turkish government.

Court documents describe the demonstration as peaceful until a group of “radicalized protesters began taunting the peaceful protesters.” The document says four men in dark clothing then emerged from the crowd and “began attacking several of the peaceful protesters.”