Medical workers treated nearly a dozen people and firefighters evacuated a building Monday after a chemical reaction caused injuries inside a manufacturing plant.

The Montgomery Fire Department said the incident happened after chemicals became mixed accidentally at Kinpak, a plastic fabrication facility.

Eleven people were affected, and three were sent to hospitals for inhalation injuries that weren’t life-threatening.

Fire Capt. Jason Cupps told WSFA-TV crews were working to ventilate the building and will be on the scene for several hours.

The public wasn’t at risk, but officials asked people to stay away from the area to give firefighters room to work.

Photos released by fire officials showed crews outside the building in protective gear.