MILTON, Mass. (AP) — A Massachusetts woman who left her 1-year-old child alone inside a truck with the heat turned up high has been charged with child endangerment, state police said.

A trooper found the child when he went to investigate a truck parked in the fire lane with its engine running at Houghton’s Pond in Milton at around 11 a.m. on Saturday, police said.

The child was sitting in a car seat in the front passenger seat conscious and alert. But state police said when the trooper opened the driver’s door, the child started to cry and the trooper felt a wave of heat because the heater was set on high.

The child was taken to Boston Children’s Hospital for observation.

State police say the truck was left unoccupied for nearly half an hour while the child's mother, a 24-year-old woman from Boston, said she was setting up for the child’s birthday party.

State police said the mother's name won't be released until she appears in Quincy District Court at a later date.