Heating oil is delivered to a home in Barre, Vermont.

Classes have been canceled at a Maine middle school after the smell of heating oil left some students and staff with headaches and nausea.

Superintendent Ken Kunin says Memorial Middle School students will attend classes at a nearby high school Thursday while workers try fix boilers blamed for the smell.

A custodian found the boiler room flooded Monday, prompting officials to cancel classes.

Students returned Tuesday, but the smell of heating oil lingered and the boilers failed again that morning.

Kunin canceled classes Wednesday, and he says he is keeping the school closed Thursday “out of an abundance of caution.”

He says the state Department of Environmental Protection tested the air quality and found it was at safe levels.

Kunin says he hopes to reopen the school by Friday.