BURLINGTON, WI (WTAQ) - Chemical fumes spreading through an elementary school in Burlington sent a dozen people to a nearby hospital Friday.

Fire officials say workers at the school had mixed some cleaning solutions which are not supposed to be mixed, causing the problem.

About 300 students were evacuated from the building to the Catholic Central High School which is next door.

The 12 people who went to the hospital were treated for inhalation of chemical fumes, with eight of them released quickly.