Story highlights Employee told police they did not count kids who were in the van

Orlando area high temperatures were in the 90s on Monday

(CNN) A Florida day care center employee is expected to face charges after a 3-year-old boy was found dead in a parked van, police in Orlando said Tuesday.

Myles Hill was found on the floor at the back of the van parked at the Little Miracles Academy day care center around 6:30 p.m. on Monday, police told reporters. Police Chief John Mina said authorities believe he had been in the vehicle since around 9 a.m. that morning. The high temperature in Orlando on Monday was about 93 degrees Fahrenheit, according to Weather Underground.

The cause of Myles' death has not been determined, but Mina said that based on the evidence, it is believed to be heat-related. "This was an absolute tragedy that could have been prevented," Mina told reporters on Tuesday.

The van is used by employees to transport children from one day care location to another -- as well as pick them up and drop them off at their homes.

Mina said an employee, who has not been named publicly, had used the van Monday to move a group of children, including Myles, from one location to another. The employee dropped the children off and returned the van to the first location at around 9 a.m. It then sat in the parking lot until police were called later that night. It was unclear whether the employee locked the van after using it.

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