Pennsylvania welfare officials have ordered the closure of a day care center after four toddlers wandered 200 yards away from it and were found by truck drivers along a busy road.

The Department of Public Welfare on Thursday accused the Walnut Grove Christian Day Care in suburban Pittsburgh of "gross incompetence, negligence and misconduct."

Department spokeswoman Stacey Witalec says the children were 3 or younger and walked the equivalent of two football fields away Tuesday. Two passing truckers saw the children and took them back to the center in West Mifflin.

Investigators say a door at the center had been propped open for ventilation and there wasn't enough staff to watch all the children.

Day care staffers referred questions Friday to attorney Stephen Plonski, who hasn't returned a telephone call seeking comment.