Twin toddler boys who were left for nine hours in a hot car outside a daycare center in Georgia likely died of heat stroke, according to a recently released coroner’s report.

Brayden and Bryson McDaniel, 20 months old, were in rear-facing car seats in their parents’ SUV after one of the parents likely forgot to drop the children off at the Sunshine House Early Learning Academy day care and went to work, said Richland County Coroner Naida Rutherford in a statement Thursday.

The brothers were found unresponsive at the end of the day when one of the parents showed up at 5:30 pm to pick them up Wednesday. It’s not clear Sunshine House Early Learning Academ ywhich parent found the children.

“If this is an unfortunate accident, we pray that the family one day finds peace,” Rutherford said, adding that authorities are continuing to investigate the deaths. “We have two very distraught parents.