SAN DIEGO >> A Southern California woman is suing the city of Carlsbad, alleging that police in the San Diego suburb unjustly beat her after she was pulled over for a seat-belt violation.

Cindy Hahn’s attorneys released a bystander’s video that shows an officer punching her and kneeing her body as another officer struggles to handcuff her on a patch of grass. Hahn is lying on her side, pleading for help before the officer ties her wrists.

The complaint, filed Friday in federal court in San Diego, says Hahn was diagnosed with head and brain contusions during a visit to the emergency room after the incident on July 31, 2013, and subsequently diagnosed with a concussion. It says the altercation caused permanent memory loss, brain trauma and other physical and emotional harm.

The lawsuit seeks unspecified damages from Carlsbad, a coastal city of 110,000 people north of San Diego, and five police officers. It alleges violation of civil rights, negligence and battery.

Carlsbad Police Chief Neil Gallucci said the lawsuit prohibited him from publicly discussing specifics. “I want to assure the public that we are prepared to provide a complete and detailed account of the facts of this incident in a courtroom, including what is not shown on the video released by the plaintiff’s attorney,” he said.

Four of the five officers named in the lawsuit remain employees of Carlsbad police, said Kristina Ray, a city spokeswoman. One officer who didn’t figure prominently in the complaint left the department last year for reasons that Ray would not disclose.

Hahn, who is represented by high-profile Los Angeles attorney Mark Geragos, claims officers retaliated against her for calling a nonemergency police hotline to report that she felt harassed by Officer Kenyatte Valentine. Hahn, then 40, was leaving a birthday party with her 11- and 7-year-old children and asked Valentine what he was doing in front of a car whose alarm had sounded. According to the lawsuit, the officer responded with a profanity.

Valentine followed Hahn in her car after she called to complain, stopped her for a seat-belt violation, ordered her to leave the vehicle, and beat her while her children waited in the back seat, according to the lawsuit. Another officer, identified in court documents as Jody Knisley, joined Valentine and allegedly punched Hahn in the face “until she was limp” and her “clothes were almost ripped off.”

The San Diego County district attorney’s office charged Hahn with resisting arrest and battery on a peace officer — both felonies — but dropped the case in July. Geragos said prosecutors dropped the case after he gave them the video.

Steve Walker, a spokesman for the district attorney, said, “When we dismiss charges, it is because we cannot prove them beyond a reasonable doubt.”

Geragos said he also shared the video with the city of Carlsbad, whose attorneys responded that they saw “no problem” with the officers’ behavior. “The video alone clearly, clearly shows felonious behavior on behalf of the officers,” Geragos said.

Geragos said he waited to file the lawsuit and share the video until police officers testified at a preliminary hearing in Hahn’s criminal case, calling it a strategic decision.

“I wanted to get the cop on the record testifying, which is astonishing if your read his testimony. He saw no hitting, didn’t see anybody hit her in the face, blah, blah, blah,” Geragos said.

The Carlsbad Police Officers Association, the union representing the city’s officers, didn’t respond to messages seeking comment.

Hahn, who is from the Los Angeles suburb of Valencia and the daughter of a reserve police officer, told KCBS-TV in Los Angeles that her son still talks about the confrontation.

“The only thing that he’ll talk to me about is, ‘I couldn’t protect you, Mom,’ ” she said.