PHILADELPHIA -- Police said they are investigating reports of sex attacks against three girls on a school bus in Philadelphia.

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Video: Mom: Girls Assaulted On School Bus

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The attacks allegedly happened Feb. 26 after the girls left Germantown Settlement Charter School, police said.

"I'm pressing charges against everybody -- the school, the people that did it to my daughter and the bus driver," said one alleged victim's mother.

The NBC 10 Investigators are hiding the mother's identity for the child's protection.

The incident involves allegations that a gang of 10- to 12-year-old students sexually assaulted her 12-year-old daughter and two other female students.

The mother insisted on telling her terrifying story seeking justice for her child.

"They actually, physically held them down, had their wrists and had their knees. The girl had both their ankles," the mother said.

The mother said what is most shocking to her is what the bus driver didn't do.

"The three girls were hollering and screaming, and the bus driver did nothing. He didn't stop, write a report, or anything. He just kept going," she said.

School officials said the driver failed to submit a written report on this incident.

The bus company said the driver did submit a report on unruly behavior but did not see a sexual assault.

School officials also said they investigated the incident, called police and kicked those suspected of wrongdoing off the bus pending the outcome of a police investigation.

Philadelphia police said they were questioning three boys accused of the assaults and a girl suspected of helping them hold down the girls.

Despite this mother's concerns, all of those students are still in school.

"She's still in school, but how is it for her to face the guys that still did this?" NBC 10's Harry Hairston asked.

"She doesn't like to talk about it at all. She doesn't talk about it all," the mother said.

A board member for Germantown Settlement said they are continuing their investigation and planning a meeting for next Monday to determine if those who are accused should be expelled.