SOUTH HOLLAND | Employees of a meat processing facility and nearby residents and business owners were allowed to return Monday afternoon after a morning ammonia leak forced an evacuation.

No one was injured after the Ed Miniat Inc. facility "completely filled with a white cloud of ammonia," South Holland Fire Chief Jim Wiley said. The leak, which occurred about 11 a.m., presented a major fire and breathing hazard, he said.

In addition to the evacuations, electricity and gas service was cut off and the facility's boilers were shut down as precautions, Wiley said.

A flange, basically two pieces of metal sealed by a gasket, was the source of the leak, Wiley said.

Authorities evacuated the facility, 16250 Vincennes Road, and about 18 businesses and residences -- totaling about 100 to 150 people -- from an area stretching about two blocks north.

The affected area was bounded by U.S. 6 on the north, Vincennes Avenue on the east, and Wallace Street on the west, South Holland Village Administrator J. Wynsma said.

The South Holland Fire Department and other emergency vehicles left the scene about 2 p.m. after a hazardous materials team found the building and area safe for employees and nearby residents to return.

A Miniat maintenance mechanic secured the leak about noon, entering the facility and leaving within a couple of minutes, said Shawna Lecuyer, the company's director of legal affairs and administration.

Once the mechanic stopped the leak, authorities opened the facility's doors and allowed the wind to naturally ventilate the building, said Wiley, who couldn't say how much ammonia was released.

"It had to be quite a large amount," he said. "It filled up most of the building, and it was a rather large building.

"It was a 2,300-pound tank, so maybe a third to a half (of that), but that's just an estimate. Ammonia expands quite a bit when it turns from liquid to (gas)."

Miniat officials were notified of the leak about 11 a.m. when an alarm sounded to indicate a leak in an isolated room at the facility, Lecuyer said. In less than three minutes, the facility was evacuated per its safety plan, she said.

"We have very good controls and our teams routinely train," Lecuyer said. "Safety is a big part of our process.

"They practice drills routinely. If it weren't for that, people may have been injured. We're very proud of our safety record, and everything went according to our safety plans."

About 250 employees work at the facility, Lecuyer said, but Monday's production schedule called for less than a full crew to be present.

Miniat, which uses ammonia for refrigeration, is a fourth-generation business headquartered in Homewood and founded by Michael Miniat. The business, which has been in South Holland since 1995, processes and fully cooks meats at the facility.

About a dozen agencies throughout the south suburbs responded to scene, Wiley said.

Authorities set up a staging area at 166th and State streets in South Holland, and traffic was detoured off U.S. 6 at 159th Street and Halsted and 159th street and Van Drunen Road. Traffic also closed off Taft Street and Vincennes Road.

Ammonia, which is heavier than air, presents an ignition danger if it were to come in contact with motor vehicles, South Holland Emergency Services and Disaster Agency Director John J. Thomas said. Extra precaution was taken because of these properties, he said.

Eighteen-year-old Cameron Snelling, who mows lawns for Thornton Township, said the smell of ammonia was apparent.

"When we came (to work at noon), we could smell a lot of ammonia outside," he said.

Another township employee thought the response was a drill.

"When I first saw (the police and fire vehicles), I thought it was a practice session (against) terrorists," John Garcia said. "This is for real."

Closer to Miniat, dozens of employees in hard hats were stretched out on a nearby lawn, waiting in the shade.

-- The Times Illinois Editor Chris Keller contributed to this report.