A 2-year-old boy died of hyperthermia yesterday after being left alone for 6 1/2 hours in a car outside a Bucks County day care center, authorities said.

The child, Daniel Slutsky, had been left in the car by Rimma Shuartsman, 46, a neighbor and operator of center who took the boy to the facility three times a week since September, said Joseph Campbell, the county coroner.