A release of ammonia forced a North Carolina food plant to evacuate, sending four workers to the hospital, according to a report. The company, which produces meat products, reported the incident on January 6 at its plant in Tar Heel, roughly 85 miles south of Raleigh.

At about 1 a.m., officials said a freezer malfunctioned, releasing ammonia into a refrigerated part of the building. According to a report from McClatchy News, the entire facility was immediately evacuated, and four employees were sent to the hospital for observation after experiencing nausea. They have since been released.