GREENEVILLE, Tenn. (AP) — Twenty-nine workers at a Tennessee cheese factory were sent to the hospital on Wednesday morning after a leak of anhydrous ammonia, Greeneville City Manager Todd Smith said at a news conference.

The Greeneville Fire Department was first called to La Quesera Mexicana at 7:15 a.m. when a leak occurred during maintenance on a valve. Six people were hospitalized at the time.

“The leak was contained and fixed at that moment. And the scene was certified as safe,” Smith said.

However, a second call about a leak came in at 10:01 a.m. A further 23 people were hospitalized and 53 other employees were evaluated for possible illness, Smith said. Anhydrous ammonia can irritate or damage the lungs and burn the eyes and skin.

Officials do not yet know if the two leaks came from the same source, Smith said, but the second leak was repaired and there was no risk to the surrounding community.

Ballad Health set up incident command centers at Greeneville Community Hospital and Johnson City Medical Center to handle the influx of patients, according to a news release from the health system. As of noon, the system was treating 25 patients from the incident.

Medical staff were working together with other emergency responders including from the Tennessee Emergency Management Agency.