The state has closed a West Mifflin day care center after four toddlers, all 3 or younger, walked 200 yards from the building on Tuesday morning and were found on the side of a busy road by two passing truckers.

The Department of Public Welfare on Thursday closed Walnut Grove Christian Day Care on Adams Avenue for "gross incompetence, negligence and misconduct."

"They walked 200 yards. We're talking two football fields. They could have been killed," said Stacey Witalec of the welfare department. "This was a mistake that could have been fatal."

The Walnut Grove staff referred questions yesterday to attorney Stephen Plonski, but he didn't return a call.

The center has the option to appeal directly to the agency, in which case an administrative law judge would hear its argument. If that fails, the center could appeal to Allegheny County Common Pleas Court.

The state doesn't often shut down day care centers, although it did close one in Lebanon County in the last year after a similar incident.

According to the state's shutdown order, the four children -- ages 15 months; 21 months; 2 years; and 2 years, 5 months -- walked out through an open door in the gym towards busy Buttermilk Hollow Road.

Two passing truckers saw them on the side of the road, grabbed them and brought them back to the center.

No one realized they were gone, said Ms. Witalec.

Police investigated and state inspectors were dispatched to check out the facility. In addition to the incident itself, the inspectors determined that the staff improperly propped open the door for ventilation and didn't have enough staffers to watch all the children.

The order also said there was a hazardous construction site outside the building, which the children walked through, and that the facility had a broken table with sharp edges that could be dangerous to children.

The order said the center "poses an immediate and serious danger to the life or health of the children in care."