The police chief of the southwestern U.S. city and state of McKinney, Texas says a white officer "was out of control" when he pulled his gun on a group of black teenagers and wrestled one of them to the ground.

Chief Greg Conley criticized the actions of the officer, Eric Casebolt, during a news conference Tuesday when he announced that Casebolt had resigned from the force.

Casebolt was one of a dozen officers responding to complaints about a noisy party at a community swimming pool Friday. Video captured by a smartphone camera shows him running and yelling obscenities at several teenagers before wrestling a bikini-clad girl to the ground with his knee and handcuffing her. During that confrontation, Casebolt pulled his weapon on a group of boys who had run in front of him.

Conley called Casebolt's actions "indefensible." "He came into the call out of control," the chief told reporters, "and as the video shows, was out of control during the incident."

The chief insisted that Casebolt was not pressured to resign.

The incident is the latest raising questions of possible racial bias by police toward African Americans in recent months.

Demonstrators gather near a community pool during
Demonstrators gather near a community pool during a protest Monday, June 8, 2015, in response to an incident at the pool involving McKinney police officers in McKinney, Texas.

The incidents have sparked nationwide protests and occasional riots, especially after deadly incidents in Ferguson, Missouri, New York City and the city of Baltimore.

Hundreds of black residents marched through McKinney Monday demanding Caseblot's firing, saying his actions were racially motivated. Police say the pool had become overcrowded, and witnesses say the teenagers failed to comply with the officers' orders to leave the pool.