SPRINGFIELD (AP) - A suspected carbon monoxide leak has forced an evacuation at a southern Minnesota school and sent 30 children to the hospital.

Police were called to Springfield Public School just after 9:30 a.m. Thursday after a couple of students reportedly fell ill in the school auditorium.

The entire school was evacuated. Hospital spokesman Kevin Burns says 30 elementary school students were taken to Mayo Clinic Health Center in Springfield with symptoms of possible carbon monoxide exposure such as nausea.

Burns says by late afternoon, 27 students were treated and released and three were still being evaluated.

Students and staff were taken to the Springfield Community Center, where students were to be picked up by parents.

Firefighters ensured the building was completely evacuated and locked.