UPDATED: 180 to Hospitals After Leak at Springdale Tyson Foods Plant

About 300 employees at Tyson Foods Inc.'s Berry Street plant in Springdale were evacuated about 9:15 a.m. Monday after workers noticed fumes in the area of the building where fresh chickens are processed.

More than 180 employees were taken by ambulance or shuttle to five area hospitals after exposure to what Tyson spokesman Gary Mickelson said turned out to be chlorine gas. Some of the workers were having respiratory problems, he said.

(Video: Scroll to the bottom of this story for a KFSM-TV, Channel 5, video report.)

"Our first and foremost concern, obviously, was ensuring that our team members were evacuated," Mickelson told the Associated Press. "... And that those who were experiencing respiratory issues as a result of the fumes were properly treated and assessed."

Publicly traded meat processor Tyson Foods (NYSE: TSN) is based in Springdale. The Berry Street plant, which produces fresh and futher processed chicken, employs about 1,200 people.

Mercy Medical Center in Rogers, one of the hospitals that received the workers, said that as of 2:30 p.m., 55 Tyson employees had been decontaminated and treated for chemical exposure. They remain under observation at the hospital.

Washington Regional Medical Center in Fayetteville said it received 33 patients from the Tyson plant. Six had been admitted with varying degrees of respiratory illness, hospital spokesman Gina Maddox said Monday afternoon.

Pat Driscoll, a spokesman for Northwest Health System, said two patients are in the intensive care unit at Northwest Medical Center-Bentonville, and another is at Northwest Medical Center-Springdale. She said 29 Tyson workers were brought to the Springdale hospital, 31 to the Bentonville facility and 24 to Siloam Springs Memorial Hospital.

All are likely to spend the night under observation, Driscoll said.

(More: What can happen if you're exposed to chlorine gas.)

The chlorine gas resulted from "an accidental mixture" of chemicals near the chiller, where the chicken carcasses are cooled, Mickelson said.

No other parts of the building were evacuated, he said, and the remaining workers at the plant were still at their posts.

In a statement late Monday, Mickelson added that, since the leak, "both the fire department and Tyson Foods have tested the air quality in the affected area of the plant and found it to be safe. As a result, second shift production started this afternoon as scheduled. Details about what led to today’s accident are under investigation."