Sheldon, Iowa (NorthwestIowaNow.com) — Authorities are confirming that students and staff at Sheldon High School were never in danger following a response to high levels of carbon monoxide in the building’s south-side construction area this morning.

Sheldon Fire, SCAT, and the Sheldon Police Department were called to the school at 8:49 a.m. Fire crews quickly isolated and contained the elevated CO readings strictly to the active construction zone. The cause was traced to a construction worker using a gas-powered buggy indoors to move cement.

Firefighters immediately evacuated all construction personnel, established continuous air quality monitoring in the main school areas, and used ventilation equipment to clear the gas.

The air quality in the student and staff areas was confirmed to be normal throughout the incident. One construction worker was transported to the hospital by SCAT, and the Sheldon Fire Department reported the scene was fully resolved, and air quality returned to normal by 10 a.m.