A New Mexico school resource officer has resigned after allegedly using excessive force against an 11-year-old girl who he alleges "took more milks than she was supposed to" from the cafeteria.

Lapel video of the Aug. 27 incident involving Farmington police officer Zach Christensen, an 11-year veteran of the department released Monday, appears to show him shoving the crying sixth grader into a wall.

The child then falls to the ground and Christensen can be heard yelling, "Stop resisting" multiple times.

The officer continues to struggle with the girl, not allowing her to stand up while asking her to put her hands behind her back.

At one point, as Christiansen stands over the girl, gripping her arm, a school administrator intervenes, saying, “Officer Christiansen, she is not a threat to yourself or others.”

Christiansen replies, “No. She is.”

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Eventually, the administrator tries to talk him down, saying, “Sir, we are not going to use excessive force to get this done.”

Christiansen then yells, “We’re not excessive!”

Farmington Police Department Chief Steve Hebbe condemned Christiansen’s actions and confirmed his removal from the department Monday in a video posted to Facebook, saying, “There’s no excuse for the way this girl was treated.”

Hebbe said that Christensen alleged that the child assaulted school staff, but added, "this proved not to be true." The officer was placed on administrative leave following the incident and an internal affairs review revealed that he had made policy violations, Hebbe said.

Hebbe also told NBC News that his department referred the case to the New Mexico state police, but that the local district attorney declined to pursue charges. However, the attorney general of New Mexico may open an investigation, Hebbe said.

On Sept. 24, Christiansen informed the department of his plans to resign effective Oct. 1. Christiansen’s supervisor, who has not been named, took a voluntary demotion and was been reassigned to street patrol after failing to "identify the incident as unacceptable", Hebbe said in his video statement.

The confrontation apparently started with an incident in the school cafeteria involving milk. “This morning, she went straight to the cafeteria,” Christiansen can be heard saying in the video. “She took more milks than she was supposed to. She threw a milk on the ground.”

Asked how he plans to prevent incidents like this in the future, Hebbe said, “That’s tough. We already feel like we have a pretty robust system in place.” But he says the department plans to review its use-of-force training.

Mark Carnutt, the girl’s attorney, told NBC News he has filed a notice of tort claim, which in New Mexico is often a precursor to filing a lawsuit.

“If a parent was doing that same thing, wouldn’t they be charged?” Carnutt said. “Is there a different standard for which police are considered for committing crimes versus other people?”