TAR HEEL, N.C. (WNCN) — Four workers were sent to a nearby hospital for treatment after an ammonia release Friday morning at the Smithfield Foods Tar Heel plant in Bladen County, according to a news release from the company

The incident happened around 1 a.m. when there was an ammonia release in the refrigerated section of the plant, the news release.

The entire plant was evacuated immediately. After experiencing nausea, four workers were sent to a nearby hospital for observation. They were later released, the company said.

All employees were then sent home after they were all accounted for, the company said.

“We have suspended operations for the remainder of the day and identified the issue as a mechanical failure in a freezer,” the news release said.

Around 4:30 a.m., another employee was found dead in his car in the parking lot of the plant, the news release said. The worker who died “did not work in the refrigerated section” that was impacted by the ammonia leak, the company said.

No cause of death of known as of late Friday afternoon. But, the company said, “there is no indication that this was related to the ammonia release.”

WECT reported that one person suffered cardiac arrest at the site, according to Bladen County Emergency Management.

About 2,500 workers were evacuated, but Smithfield Foods said there were fewer than 800 at the plant at the time of the evacuation, according to WECT.

Officials said they plan to resume plant operations on Saturday.