MISSION — Six people are recovering after a chemical spill inside a Johnson County veterinary clinic sent them to the hospital.

The Kansas City Star reports that a gallon of formaldehyde spilled Wednesday inside the Mission Veterinary Emergency & Specialty clinic. Arriving firefighters learned that while the spill had been cleaned up, several people who had interacted with the chemicals were ill.

The Overland Park Fire Department hazmat team was called in, and the building was evacuated. Six people were treated at hospitals and released.

Firefighters used fans to ventilate the building, and employees were allowed back in hours later.