WEST MEMPHIS, AR (NBC NEWS) – A five-year-old boy was found dead on a daycare bus Monday in Arkansas.

West Memphis Police Department said Christopher Gardner Jr. was found dead at 3:30 p.m. on Monday, WMC reported.

Police say the child was left in the van, in the hot sun for more than eight hours.

They say the boy was picked up from his home before 7am, but never left the bus. Police say he was in a booster seat, but it’s not clear why he did not or could not get out.

He was not found until 3:30pm.

The van belongs to Ascent Children’s Health Services.

An investigation is underway, but no arrests have been made.