About 35 Tyson Foods workers were evacuated for nearly two hours early this morning following an anhydrous ammonia leak.

At around 4 a.m., Bovina volunteer firefighters were called to the Flowers business after employees smelled the chemical, said Johnathan Priddy, incident commander for the Bovina Volunteer Fire Department.

The chemical is considered hazardous. Priddy said it is used in refrigeration.

The amount of ammonia, which leaked from a coil house inside a spiral freezer, was not enough to measure, he said.

“It wasn’t dangerous at all,” said Priddy. “It was a safe environment for (employees) to return to.”

Workers including refrigeration technicians and a sanitation crew returned to work at about 5:40 a.m., Priddy said.

He said he did not know what caused the leak.

Firefighters and Tyson’s hazardous materials team investigated the leak.