Authorities are investigating a graphic incident in Los Angeles after a cellphone video emerged of a police officer punching a Black woman on the side of a highway.

In the video, which was recorded along the Santa Monica freeway last Tuesday, 51-year-old grandmother Marlene Pinnock is seen being pulled to the ground by an unidentified California Highway Patrol officer and pummeled more than 11 times in the face. It is unclear why Pinnock was walking along the highway at the time or what started the confrontation, although she does not appear to resist.

"The focal point of what she did on the freeway is simple. She got beat, savagely beat by someone who seemed to be trying out for mixed martial arts. And it's unacceptable," said the woman's attorney, Caree Harper.

CBS News reports that Pinnock is currently in a medical facility under an involuntary psychiatric hold.

"They wouldn't let me see her,” Pinnock’s daughter told reporters, referring to the police, who she claims kept family members at bay for a week. "I don't know what was going on, but today was the first day that I was finally able to see her and talk to her and I just thank God that's she's alive," the daughter said.

While Harper alleges that Pinnock has suffered multiple injuries and "is having to press ice compacts repeatedly on her body, face, arms, shoulders,” the arrest report stated that the woman “did not advise of any” injuries.

The officer has been put on administrative leave while the California Highway Patrol investigates. The department believes there is no need for an independent investigation, but community activists and civil rights groups are demanding a federal investigation.

"Speaking for the women of this community, we are angry, we are upset," said Lita Herron of the Youth Advocacy Coalition.

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 (Photo: AP Photo/David Diaz)