Meghan Bodette, who identified herself as one of six protesters (one of whom was filming), said their goal was “to call attention to the Turkish state’s war crimes and human rights abuses against the Kurdish people,” both in Turkey and in Syria.

“Erdogan should not be able to speak here unchallenged, and we challenged him because the American people need to know that a state that claims to be our ally is hindering the fight against ISIS in Syria and destroying civilian lives,” Ms. Bodette said in a Twitter message.

Halil Demir, a Turkish-American who works for a humanitarian organization, said he had been standing near the back of the room when three protesters stood up in rapid succession: a young man, a young woman and a middle-aged man. The woman held a green banner, Mr. Demir said. Ms. Bodette identified it as the flag of the Women’s Protection Units, or Y.P.J., the female counterpart to the Y.P.G.

The young man was pulled out of the room, Mr. Demir said, and the woman left on her own after being told to do so. But Mr. Demir said he saw security guards push the middle-aged man, who fell to the ground. He did not know whether the guards were part of Mr. Erdogan’s detail, the United States Secret Service or the hotel’s security team.

“The third man screamed, and people were screaming at him,” he said. “It didn’t take long. Seconds, really.”