The Hannibal Fire Department was called to the building housing the Marion County Services for the Developmentally Disabled office in Hannibal about 10:30 a.m. Tuesday.

Officials in the office told the Courier Post that three people in the office complained of dizziness and headaches. That’s when the fire department was called in to check for carbon monoxide leaks.

About 25 to 30 clients and staff were evacuated from the building for about a half hour. After tests found no traces of carbon monoxide in the building, firefighters sounded the all clear about 11:15 a.m.

There were ambulances dispatched to the scene, but they weren’t needed.