GROVETON, N.H. (AP) – A northern New Hampshire elementary school was shut down for a day Tuesday after tests found high carbon monoxide levels there.

Students had barely arrived at Groveton Elementary School when they were loaded onto buses again and evacuated.

Only a few children entered the building for breakfast before the evacuation, and emergency workers gave them a clean bill of health, Principal Carl Ladd said.

Firefighters detected the carbon monoxide in the school’s kitchen. Officials said a faulty oven may be the problem.

The ovens have been shut off and the building has been ventilated, allowing the school to reopen Wednesday, officials said.