A 6-year-old New Jersey girl who died on a school bus "struggled violently for her life" while a bus monitor sat nearby, staring at her phone with earbuds in, police said.

Newly released surveillance camera video shows Fajr Atiya Williams, a student with special needs, being strangled by her seat belt while school bus aide Amanda Davila, 27, sat oblivious just feet away, according to a criminal complaint obtained by NJ.com. For nearly a quarter of an hour, Davila paid no attention to the non-verbal girl in a wheelchair as she suffocated to death, police said. 

Davila is now charged with manslaughter. 

Detectives with the Franklin Township Police Department and the Somerset County Prosecutor’s Major Crimes Unit said Fajr boarded the bus to attend an extended school year program at Claremont Elementary School on July 17. Davila brought the girl aboard the bus at 8:29 a.m. using a hydraulic lift for her wheelchair, the complaint states. 

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Amanda Davila appears in Superior Court in Somerville

Amanda Davila appears in Superior Court in Somerville. The school bus aide is charged with manslaughter in the strangulation death of a non-verbal disabled child in her care. (Alexander Lewis/MyCentalJersey/USA Today Network)

According to police, Davila secured the wheelchair to the floor hook on the rear driver's side of the bus. She secured Fajr with a four-point harness but neglected to use the lap belt and ankle restraints on the wheelchair, authorities said. 

At around 8:44 a.m., the bus hit bumps in the road that "made the four-point harness become tight around her neck," the complaint said.

Investigators who reviewed the surveillance footage said Fajr "appeared to be moving her mouth at that point in the video." Then at 8:46 a.m., the harness tightened around Fajr's neck and for the next 2 minutes and 47 seconds, she "struggled violently for her life, flailing her arms and legs."  

At least twice, Fajr "made a shriek or gasp and at one point kicked the window of the bus," the complaint states. 

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Amanda Davila mugshot

Amanda Davila was charged with second-degree manslaughter and second-degree endangering the welfare of a child after a 6-year-old with special needs died while riding a bus under her supervision. (Somerset County Prosecutor's Office)

The girl lost consciousness at 8:48 a.m., but Davila did not realize anything was wrong until the bus arrived at the school in Franklin Township at 9:02 a.m. – 14 minutes later.

Once she began to undo the floor restraints, Davila noticed something was wrong and contacted a school staff member for help, police said. 

"At 9:02:58 a.m. a teacher entered the bus and tended to [Fajr], but appeared to not yet realize the dire nature of the situation. At 9:04:00 a.m. the teacher stated that she was unsure if [Fajr] was breathing. At that point additional staff was summoned onto the bus and CPR began at 9:06:40 a.m.," the complaint said, per NJ.com. 

Fajr was transported to a local hospital and placed in intensive care before being pronounced dead on Wednesday, authorities said.

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School bus

Six-year-old Fajr Atiya Williams died after riding on a school bus when the harness that secured wheelchair tightened and blocked her airway. The school bus monitor was charged with manslaughter. (iStock)

The two other students on the bus were sitting in front of Fajr, and neither had a direct line of sight to her as she struggled, the complaint said. 

Investigators said Davila violated policies and procedures by allegedly wearing earbuds and using her phone on the bus.

She was charged with second-degree manslaughter and second-degree endangering the welfare of a child.

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Davila appeared in court last week and is scheduled for a detention hearing Tuesday. She is being held in the Somerset County Jail. 

Fajr's mother, Najmah Nash, created a GoFundMe fundraiser to help cover the costs of her daughter's funeral and outstanding medical expenses the family faces. 

"My family and I are truly devastated by this and would appreciate anyone that can help," Nash wrote. 

Fox News' Greg Wehner contributed to this report.