"Customary international law affords heads of state and members of their entourage with inviolability from arrest and detention," the official said. "The United States recognizes this inviolability, which provides reciprocal protection for the United States abroad."
However, the State Department did say that the investigation will "hold the responsible individuals accountable."
The State Department also said that acting Deputy Secretary of State Tom Shannon spoke with Turkish Ambassador Serdar Kilic about the fighting that left at least nine injured, including a DC police officer. Shortly after the incident, Kilic was recorded shouting "You cannot touch us!" at DC police, likely referring to his diplomatic immunity.
On Tuesday, a group of about two dozen protesters gathered outside the Turkish embassy to protest the Erdoğan regime, specifically his treatment of Turkey's Kurdish minority. The peaceful protest rapidly descended into a street fight as men in black suits appeared from seemingly nowhere. DC police tried in vain to restore order.
Congressmen like John McCain (R-AZ) are demanding a decisive response to the Turkish officials' actions. During an appearance on MSNBC's "Morning Joe" talk show, McCain said that "we should throw their ambassador the hell out of the United States of America."
"This kind of thing cannot go un-responded to diplomatically," said McCain, suggesting that the US sue the Turkish government if the bodyguards responsible for the violence can't be identified.
WATCH: President Erdoğan sat in his car and watched his security detail attack protestors outside the Turkish Embassy in Washington DC. pic.twitter.com/WB70f7xmDo— Yashar (@yashar) May 18, 2017
Senator Claire McCaskill (D-MO) agreed with McCain in a tweet: "Unacceptable. They were assaulting these people on US soil. Turkish Ambassador should be kicked out of country."
The Turkish embassy issued a statement on Wednesday that the protesters were "affiliated with the PKK (Kurdistan Workers Party)," which Turkey considers to be a terrorist group. They "began aggressively provoking Turkish-American citizens who had peacefully assembled to greet the President."
"The Turkish-Americans responded in self-defense," the statement read. "We hope that, in the future, appropriate measures will be taken to ensure that similar provocative actions causing harm and violence do not occur."