UPDATED 06/07/12 7:50 a.m.

CHICAGO (CBS) – A school bus driver is the subject of a lawsuit filed by a Willowbrook couple that claims he sexually assaulted their 3-year-old twin daughters.

The lawsuit follows a story on the case by CBS 2 Investigator Dave Savini.

As WBBM Newsradio’s Michele Fiore reports, the parents filed the lawsuit anonymously in Cook County Circuit Court. The 3-year-old girls ride the bus to special education preschool classes at Gower West Elementary, 7650 Clarendon Hills Rd.

LISTEN: WBBM Newsradio’s Michele Fiore reports

“Every time I see a school bus I panic because I don’t know how many other kids this has happened to,” the distraught Willowbrook mother told Savini recently.

The parents claim the bus driver began a friendship with the children by offering them candy and treats, and began sexually abusing them in October 2011.

The abuse continued through January 2012, the lawsuit said.

Sources say the bus driver allegedly told investigators one of the 3-year-olds made advances towards him.

The suit claimed the driver rearranged the students’ drop off schedule so he would be alone with the twins, and sexually assaulted them after parking the bus near their Willowbrook home. No other chaperones were present when the alleged abuse happened.

“It just seems that their innocence has been taken from them at the age of 3,” the girls’ father told Savini.

The driver declined to comment to Savini. But officials for Grand Prairie Transit confirmed he was fired after a state investigation revealed this month there is “credible evidence of child abuse and/or neglect.”

The Illinois Department of Children and Family Services began investigating the driver, a Berwyn resident, on January 6, spokesman Kendall Marlowe said. The investigation concluded May 5 and substantiated allegations of abuse relating to two children, he said.

The driver was added to the state’s central register for child abuse and neglect, which some employers are legally required to reference while conducting background checks on potential hires.

A DuPage County Circuit Court judge ordered the bus driver to stay away from the family though at least 2014, but a representative of the DuPage County State’s Attorney’s office had no immediate information on whether criminal charges have been filed in connection with the case.

The suit blames the bus driver’s employer, Grand Prairie Transit, for not equipping its buses with cameras, recorders or GPS tracking devices, the suit claims.

“We had a system failure here,” Tony Romanucci, who is the attorney representing the family and the twin girls, said last week.

It also names as defendants the school district and the LaGrange Area Department of Special Education, which provides special education classes to students in 16 districts and arranged for the bus service in conjunction with the district. Both failed to provide students safe transportation to and from school, the parents claim.

The 11-count suit claims battery and infliction of emotional distress against both the driver and Grand Prairie Transit, as well as an additional count of negligence against the bus company.

It suit also claims willful and wanton conduct against Gower School District, LADSE, and a LADSE board member. It also makes a claim under the Family Medical Expense Act against all of the defendants.

None of the defendants could be reached for comment Wednesday evening.

The suit seeks at least $550,000 in damages plus the costs of the suit.

The parents of the twin girls who were allegedly abused also want a state law making cameras and GPS systems mandatory on all buses.

The Sun-Times Media Wire contributed to this report.