5-year-old Arkansas boy dies after being left in hot van at day care

— -- The Arkansas Department of Health is investigating the case of a 5-year-old boy who died after being alone in a hot day care vehicle for hours, authorities said.

Christopher Gardner was found unresponsive in a sealed van parked outside Ascent child care center in West Memphis, Arkansas, according to police. The facility cares for children with special needs.

An employee had reportedly picked the child up to transport him to school Monday morning but he was never taken off the bus. The exact cause of death is still under investigation, but the heat index reached nearly 100 degrees Monday afternoon in West Memphis.

"We're working to see whether the policies were followed," Arkansas Department of Human Services spokeswoman Amy Webb told reporters Tuesday. "Clearly, they weren't in this case. So we need to find out what the breakdown was, how that breakdown happened and then were people properly trained?"

The agency said the driver and the child care staff member are required to walk to the back of the vehicle to check each seat. Child care centers are also supposed to compare the transportation roster with the class attendance sheet to make sure each child is accounted for, according to DHS.

Christopher's mother, Ashley Smith, said she is desperate to get to the bottom of the incident.

"I just need some answers," Smith told ABC Memphis, Tennessee, affiliate WATN-TV Tuesday. "I've never been through this in my life. I wouldn't put nobody through this."

Ascent issued a statement Tuesday, saying it was "heartbroken" by the child's death.

"There are simply no words to express the overwhelming sadness we feel at the death of this child," Ascent Children's Health Services said in the statement. "We are heartbroken and our thoughts and prayers go out to the family."