A 6-year-old girl with special needs died in New Jersey this week after her wheelchair harness constricted her breathing while she was riding a school bus, leading prosecutors to charge the bus monitor with manslaughter, officials said.

An investigation revealed that the bus monitor, 27-year-old Amanda Davila, secured the child in her wheelchair at the rear of a school bus on Monday, the Somerset County Prosecutor's Office said.

During the bus ride, a series of bumps in the road caused the 6-year-old to "slump in her wheelchair seat," which led the harness securing her to the chair to become tight around her neck, eventually blocking her airway, the prosecutor's office said.

Davila was seated toward the front of the bus, using her cellphone with headphones in both ears, during this time, according to the office. "The investigation revealed that this was in violation of policies and procedures," it said.

The Franklin Township Police Department responded to a local school around 9 a.m. after receiving a call about an unresponsive juvenile, according to prosecutors. Officers performed CPR on the child and she was transported to a hospital's intensive care unit, where she was pronounced dead, it said.

Davila was placed under arrest on Wednesday and charged with second-degree manslaughter and second-degree endangering the welfare of a child, prosecutors said.

Davila is being held in Somerset County Jail and is awaiting a detention hearing. CNN has been unable to determine if she has retained an attorney at this time.

Prosecutors did not identify the school the child attended. Franklin Township is about 30 miles southwest of Newark, New Jersey.