Ammonia leaking from a refrigeration plant in Alabama on Monday sent more than 100 local residents to hospitals, police said.

According to officials, as much as 300 gallons of ammonia escaped from the Millard Refrigerated Services plant in Theodore, Alabama. Nearby residents and factory workers complained of eye irritation, dizziness, sinus pain and difficulty breathing, according to emergency workers.

Residents in nearby homes reported seeing a large, white cloud of gas rising from the plant. The incident lasted about 30 minutes.

All people residing within one mile of the plant were urged to stay indoors and to cease using their air conditioning until authorities declared it safe to do so.

The plant, which packages frozen chicken products, uses ammonia in its refrigeration process.