Two girls, aged ten and eight, and two boys, both aged four, were found dead in the car, one of several vehicles seized by a bank for default in loan repayment and kept at a yard in Vedanatham near here, police said.
The children had come to the place for a temple function along with their parents and were playing in a nearby area.
"They were playing in the vicinity and had later got into a car. It seems the car's doors got locked automatically. They suffocated to death," a police official said adding further investigation was on.