Little five-year-old Christopher Gardner, Jr. was picked up by the Day Care van at 6:40 a.m. on Monday, to be taken to Ascent Children’s Health Services in West Memphis, Ark., a day care and health facility for children with developmental disabilities. However, the boy was never taken out of the van and was found dead in his booster seat eight hours later from the sweltering heat of the day.

Investigation launched into why the alarm in the day care van did not sound

The Arkansas Department of Human Services has launched an investigation on Tuesday to establish why the van’s alarm system and other security safeguards in the vehicle did not react to the situation.

All vehicles operated by child care services in the state that carries more than seven children are subject to certain safety requirements, including child safety alarms. However, in this case, the alarm did not sound.

According to Christopher’s mother, Ashley Smith, he has attended the day care since he was one year of age, due to a heart condition and has undergone two heart surgeries in his short life. She said her son was collected from her home at 6:40 a.m., and that is the last time she saw him alive.

The day care van reportedly arrived at the day care at 7:20 a.m.

but Christopher was never removed from the vehicle. WMC Action News 5 reports that there was a driver and one other adult in the van with the children. Sources told the news service that the child was signed into the day care facility, despite the fact he was still sitting in the van.

Boy found eight hours later, still strapped in his seat

According to police, Christopher was found, still strapped in his seat, around eight hours later as staff from the day care began to load children for their journey home.

While the five-year-old’s cause of death has not yet been released, temperatures reached 80 degrees in the van, which reportedly caused the temperature in the van to rise to around 114 degrees within 30 minutes of the boy being inside the vehicle. According to investigators, the heat would have risen to around 141 degrees during the time he was inside the van.

A statement by Ascent Children’s Health Services expressed their “overwhelming sadness” at the death of the boy, saying they are “heartbroken.”

ABC News reports that the Arkansas Department of Health has closed the facility for the remainder of the week over a shigella outbreak. Police have not said whether charges will be filed against the day care center relating to Christopher’s death.