YAKIMA, Wash. — Classes at Davis High School are canceled today due to an “unusual odor” that materialized Thursday in part of the construction zone of the building’s remodeling project.

The Yakima School District called the cancellation a precaution, saying the odor is within a mechanical room, but did not identify a source.

Athletic activities scheduled for this weekend — today, Saturday and Sunday — will continue as they are out-of-town games, the district said in a news release. Classes will resume Monday pending further announcements, the district said.

The notice that school was canceled came just hours after four construction workers left the Davis site complaining of breathing problems. They were treated in the emergency room of Yakima Regional Medical and Cardiac Center.

The likely cause of the problem was gray smoke generated from demolition of a cooling unit inside the school, said Tom Sevigny, a battalion chief for the Yakima Fire Department. A torch used to demolish the unit likely vaporized residual gas inside.

By Thursday afternoon, several workers were having trouble breathing and went to the hospital, Sevigny said. They were expected to be treated and released.

The Yakima Fire Department and state Department of Ecology were at the school for an inspection.

Students and faculty still inside Davis were evacuated from the building.