An ammonia leak at the Tyson Foods in Wallula forced a temporary evacuation of part of the plant, but no injuries were reported.
Firefighters from Walla Walla Fire District 5 in Burbank were called to the plant around 10 a.m. Thursday for a hazardous material response in the mechanical room.
Chief Mike Wickstrom said a seal in a valve failed on a line of ammonia, causing ammonia to get dumped onto the floor.
The workers were evacuated and the company's own hazardous material response team responded and were able to isolate the leak and shut it down before fire crews arrived, Wickstrom said.
His crews then verified everything was OK.
"The problem with ammonia is you definitely don't want to breathe it, especially in liquid form," Wickstrom said.
Tyson's team was able to quickly shut down and drain the system, keeping the incident contained to just the mechanical room.
"They did a great job," he said.
The processing area of the plant was not affected.