Officials closed Longfellow Elementary Monday after carbon monoxide was detected.

Students were not allowed to enter the building and were sent home, and parents were contacted to make sure children got home safely.

The cause of the carbon monoxide was believed to be the boiler system in the building, according to a press release from the Iowa City School District.

MidAmerican Energy, as well as the Fire Department responded to the scene, according to the press release.

— by Allie Wright