McKinney police corporal Eric Casebolt attempting to wrangle teenagers attending a pool party in McKinney, Texas, on Friday. Screenshot A police corporal seen on video forcing a teen girl to the ground and pointing his gun at other children during a pool party has resigned.

A lawyer for McKinney, Texas, police corporal Eric Casebolt told a local news station that Casebolt issued his resignation Tuesday, days after video of the incident went viral.

In a news conference Tuesday afternoon, McKinney police chief Greg Conley said Casebolt was "out of control" and called the officer's actions "indefensible."

Conley also said that out of the 12 officers on scene that day — Casebolt among them — "11 acted properly."

The policeman had been placed on administrative leave shortly after the video surfaced.

FOX4 news in Dallas said it was not clear how Casebolt's resignation, which was apparently tendered on his own volition, would affect an ongoing internal investigation into the incident. That investigation is expected to wrap up as early as the end of the week, the station reported.

Hundreds of protesters rallied Monday against what demonstrators called police brutality in McKinney, Texas. Hundreds marched through the Dallas-area city of McKinney calling for the firing of police officer Eric Casebolt, seen in a video throwing a bikini-clad teenage girl to the ground and pointing his pistol at other youths at a pool party. REUTERS/Mike Stone The video shows Casebolt and several other officers arriving at a residential neighborhood in McKinney on Friday on a call of some sort of disturbance at a pool party.

The incident appeared to quickly escalate as Casebolt chased teenagers, many of whom were black, and ordered them to the ground. At one point, Casebolt pulled his gun on a group of teens standing nearby. The teens quickly ran away as two other police officers grabbed Casebolt and pulled him back.

The part of the video that has gained national attention is when Casebolt detains a 15-year-old girl who was wearing a bikini. Casebolt can be seen forcing the unarmed girl to the ground and sitting on her back as she lay facedown in the grass.

You can see a portion of that exchange here: