An American mother is suing the city of Carlsbad, California, alleging a police officer punched her in the face during an arrest while her young children were looking on, court records show.

The 40-year-old mother was leaving a birthday party with her two children, aged 11 and 7, on July 31, 2013 when the incident happened.

The violent action by police was triggered when Cindy Hahn asked a cop with the City of Carlsbad Police Department why he was standing in front of a car doing nothing as its alarm went off.

“He says, ‘Is this your car?” And I said, “No, sir.” And then he says “Then, mind your own f**** business,” she said.

The officer continued swearing at her, Hahn said, adding that she reported the incident to police, but then left the scene.

A short while later, the same officer “immediately pulled her over on the pretextual grounds that the driver of the vehicle had a seatbelt violation,” according to the complaint.

The cop then forced the woman to the ground with other officers arriving at the scene and an officer punched her in the face, according to Hahn and a video clip.

It can be seen in the clip that a third police officer is keeping witnesses away from the woman, who is finally helped to her feet as an officer in a motorcycle helmet hikes down her dress.

“I can feel hands on me. It’s the weirdest feeling,” she said.

“She was at the party; she’s one of the family members. She didn’t do anything. I came out, I heard her screaming. They’re jumping on her and beating her up,” a woman who filmed the incident can be heard saying in the video. “She didn’t do anything wrong. Nothing.”

Hahn suffered memory loss and brain trauma because of the incident, according to court documents.