The security video shows a 14 year-old mental patient being escorted down a hallway when a Pembroke Pines police officer reaches in and grabs the girl. The girl whirls and swats at the officer, and he proceeds to punch her in the face. The officer's blow to the mentally disturbed teen snapped her head back, and appeared to be delivered with full force. Other officers join in, wrestling the girl to the ground and spraying her with Mace.

"It was shocking to see the amount of violence that occurred. It was shocking," said Assistant Broward County Public Defender Jeff Hittlemen.

The incident happened at the Citrus Health System treatment center for mentally disturbed adolescents on April 28th. The place treats children, many under contract with Florida's Department of Children and Families.

The public defender's office got involved in the case of the disturbed girl slugged by the cop, after police subsequently charged her with resisting arrest.

Broward's Chief Assistant Public Defender, Gordon Weekes, Jr., said officers had to have known they were dealing with a deeply disturbed teen.

"They are acting out in their mental illness," Weekes said, "And to draw off and strike a child in the face with enough force to try to knock her head off is nothing more than an excessive use of force."

The public defenders uncovered what they're calling systematic use of physical and chemical force to restrain patients at the Pembroke Pines Facility. They said their investigation revealed kids are routinely tied hand and foot to their beds and administered drugs to knock them out.

Weekes said his office conducted five, separate interviews with clients at the facility, all of whom said they had essentially been hogtied and injected - knocked unconscious.

Dr. Michael Jochananov, the facility's director, declined to speak with CBS4′s Gary Nelson at the center Thursday.

"Sir, I'll have to refer you to our main center," Jochananov said. "I have to get back to may clients now, thank you very much."

An attorney for Citrus Health Systems, Josephine van Hemert, said the clients at the facility are seriously mentally ill, and called the public defender's allegations "a misrepresentation of procedures used to restrain these children when they are out of control or attempting to hurt themselves or others."

Citrus Health said it welcomes an investigation. It will get one.

By the end of the day, the Department of Children and Families, The Agency for Healthcare Administration and the Pembroke Pines police department said they would investigate allegations of abuse of children at the facility.

According to the public defender's office, the law does not permit such facilities to use "chemical restraints" on clients as a substitute for a lack of adequate staff.

As for the officer who struck the 14 year-old patient, a Pembroke Pines police spokesperson said the girl struck the officer first.

Captain Al Axiques told CBS4 the officer and others were at the facility in response to a report of a "riot" among patients called in by staff members at the facility who reported they had "lost control" of the institution. Axiques said the situation was so severe that Mirarmar police officers had to be called in to help restore order.

The "riot" at the facility intended to treat severely mentally ill children may raise questions regarding the contractor's ability to manage the institution and carry out its responsibilities under contracts with various agencies and its license, issued by the Agency for Healthcare Administration.

Citrus Health's counsel, van Hemert, issued a statement Thursday afternoon saying, "Citrus Health Network will conduct a thorough internal investigation into these allegations. We also welcome the Florida Department of Children and Families, and the Agency for Health Care Administration to conduct their own investigations into this matter."