 Story highlights Day care staff found 5-year-old boy dead inside van on Monday afternoon 
 
 Staff did not follow policies and procedures, day care CEO says 
 
 (CNN) Four Arkansas day care employees were fired Wednesday after the death of a 5-year-old who was left inside a van all day. The exact cause of death is still under investigation, but the heat index reached nearly 100 degrees Monday afternoon in West Memphis. Play Facebook 
 
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 The facility, Ascent Children's Health Services of West Memphis, serves children needing occupational physical therapy and special needs services.
– Police in Arkansas are investigating how day care workers could have left a 5-year-old boy in a sweltering van for hours, NBC News reports. Christopher Gardner Jr. was found unresponsive, strapped into a booster seat at 3:30pm on Monday. That was more than eight hours after the van had arrived at Ascent Children's Health Services, per WMC, and only as it was time to drive the kids home. Administrators at the day care center for special needs children fired four workers Wednesday for failing to follow procedures, reports CNN. "There are simply no words to express the overwhelming sadness we feel at the death of this child," Ascent CEO Dan Sullivan says in a statement. "We are heartbroken." Workers are required to walk to the back of the van and check each seat, and then verify the van's roster with a class attendance sheet to ensure all the kids are accounted for, reports ABC News. West Memphis police tell CNN that temperatures in the parking lot were 91 degrees on Monday when they arrived, and that Christopher may have been asleep when the van arrived at the facility. They say the temperature inside a nearby sealed van was measured at 141 degrees, notes NBC. "I just need some answers," says Christopher's mother, Ashley Smith, per ABC. "I just want justice for my son." Great-grandmother Carrie Smith tells WMC that Christopher "suffered in that van." She says they had a routine when Christopher came home each day. "When he got off the van he'd say, 'Granny, have you got me a cookie today?'" (Two toddlers died last week after being left overnight in a hot car.)