D.C. Police announced that they will pursue additional charges in the melee that erupted outside the Turkish ambassador’s residence in Sheridan Circle Tuesday night between protesters and guards for Turkish President Recep Tayyip Erdogan.

“We are going to pursue everything that’s within our legal power to hold the folks that were responsible accountable for their actions,” D.C. Police Chief Peter Newsham said at a press conference this afternoon. “We intend to ensure there was accountability for anyone who was involved in this assault.”

In a statement, the State Department identified those involved as Turkish security personnel. “Violence is never an appropriate response to free speech, and we support the rights of people everywhere to free expression and peaceful protest. We are communicating our concern to the Turkish government in the strongest possible terms,” spokesperson Heather Nauert said.

Newsham stopped short of identifying the assailants as Erdogan’s guards, but he noted that diplomatic immunity issues may come into play. He also said the department is working with the State Department and the Secret Service to identify assailants in multiple videos of the incident.

“We have very good video. We have a good idea of some of the folks that were there on the scene. We’re very comfortable that we will be able to identify most of the assailants,” Newsham said.

A state-owned Turkish news agency reported that the president’s security team was involved in the fighting outside the embassy, the New York Times reports. U.S. officials also confirmed to NBC News that Erdogan’s bodyguards beat protesters.

The Metropolitan Police Department made two arrests on the scene. Ayten Necmi, of Woodside, New York, was arrested for aggravated assault and Jalal Kheirabaoi of Fairfax, Va. was arrested for assault on a police officer.

Newsham said that the Secret Service also arrested two more people, but it is unclear if they were charged.

Erdogan visited with President Donald Trump earlier in the day, where he received a warm welcome. A group of protesters demonstrated in Lafayette Park before heading up to the Turkish ambassador’s residence near Sheridan Circle when they learned that Erdogan would make a stop there, the executive director of the Armenian National Committee of America told the New York Times.

About two dozen people were protesting, while a group of men in suits stood near the ambassador’s residence. Verbal confrontations between the two groups turned to violent skirmishes, which were broken up by local and federal police officers. Videos showed armed men in suits kicking and punching protesters.

“The police involvement in that case was very dicey because there were some people up there that had firearms, and they had to safely restore order. Thankfully that was done without more significant injury,” Newsham said at today’s press conference. He added that MPD was investigating whether the presence of guns was in violation of D.C. law, which has tight firearms restrictions.

Nine people were transported to the hospital, one with serious injuries. The incident also caused extended road closures around Sheridan Circle during rush hour.

“They think they can engage in the same sort of suppression of protest and free speech that they engage in in Turkey,” protester Flint Arthur told CNN. “They stopped us for a few minutes … but we still stayed and continued to protest Erdogan’s tyrannical regime.”

It isn’t the first time that the Turkish president’s visit to Washington turned violent. Security guards for Erdogan clashed with protesters, journalists, D.C. Police, and staff at the Brookings Institution last March during a speech he was giving at the think tank.

Newsham said it remains to be seen how many assailants that MPD is looking for, and is asking anyone with more information or additional video footage to contact the department.

“What we saw yesterday—a violent attack on a peaceful demonstration—is an affront to D.C. values and our rights as Americans,” Mayor Muriel Bowser said in a statement.

U.S. Senator John McCain tweeted, “This is the United States of America. We do not do this here. There is no excuse for this kind of thuggish behavior.”

Added Newsham: “That’s not something we will tolerate in Washington, D.C. This is a city where people should be allowed to come and peacefully protest.”