A mother is behind bars accused of taking part in a fight with her two teenaged daughters that was caught on camera, police said Wednesday.

According to McKeesport police, the mother and her two daughters can be seen in cellphone video that was posted online beating up another young woman.

Arlen Harper said he first came across the footage on Facebook.

"I sat there, and I watched it in disbelief,” he said. "I think it was senseless. I think it was unacceptable for all the adults who were standing there watching it."

Harper and his family said they want justice for the young woman who was repeatedly punched and slammed to the ground.

Investigators  said they arrested the mother, identified as 38-year-old Sandra Jackson, an hour after the fight. Their investigation into what led to the fight continues.

Police said the victim told officers that she was jumped, but Jackson told investigators that the girl was looking for trouble.

Regardless, Shawanda Little-Dreher, a former Crawford Village resident, said the video is sad.

"We need our mothers and fathers to raise these kids to be better and more productive citizens. They are our future,” she said.

Authorities said the victim had some cuts and bruises but refused medical treatment.

Jackson faces a list of charges, including aggravated assault.

At this time, there is no word on whether Jackson’s 18- and 19-year-old daughters will also face charges.