WATERLOO - The presence of immigration officials at National Cattle Congress has stoked fears of an impending raid and caused some in the Hispanic community to avoid workplaces and public areas.

Four days after The Courier first reported the installation of trailers, generators and ventilation equipment on the grounds, the presence of the U.S. Immigration and Customs Enforcement remains a mystery. Tim Counts, an ICE spokesman in the Twin Cities, refused comment on Tuesday. He said he didn't know when, or if, the agency would explain its activities.

NCC officials said they were told the grounds were rented for a training exercise and that the Federal Emergency Management Agency was involved. FEMA and ICE both fall under the command of the U.S. Department of Homeland Security.

On April 24, FEMA announced it was conducting a national-level training exercise in May "to prepare and respond to multiple incidents including both natural disasters and terrorist incidents." Exercise scenarios included a Category 4 hurricane impacting the mid-Atlantic coast and the national Capitol complex; multiple terrorist attacks in Washington state; and an accidental chemical release at a chemical depot in Oregon.

The FEMA release did not specify the location or locations of the exercise, some of the objectives of which are to test communications and interagency coordination.

While the release indicated "a combined functional and full-scale exercise" would be conducted May 1-8, the government has leased the NCC grounds through May 25.

Neither NCC nor the federal government would confirm whether federal officials are using the NCC grounds as part of the national exercise. In response to an inquiry by The Courier, U.S. Sen. Charles Grassley's office requested a briefing on the use of the NCC grounds, but was told ICE officials would neither confirm nor deny anything. Similarly, U.S. Rep. Bruce Braley's office was unable to obtain additional information.

Mark Grey, an immigration expert and University of Northern Iowa professor, said the grounds at NCC appear to have a capacity similar to that the Iowa National Guard armory in Fort Dodge. That is where authorities held suspects after a 2006 raid of a Swift meat processing plant in Marshalltown.

But in that instance, he said, authorities kept their plans secret.

"I ask myself, 'What are they planning, and why are they being so bloody obvious about it?'" he said. "Maybe it is a training exercise, but why would they go to all that expense?"

Laura de Gomez, owner of La Placita, a grocery store and restaurant, said she received a call Sunday from a woman wondering if it was safe to make a trip to the store for food. It is one of many frantic calls and questions de Gomez and other leaders in the Latino community have fielded in recent days.

Not everyone concerned about an immigration raid lives in the country illegally, de Gomez noted. Many legal residents have family and friends at risk of deportation.

Gomez and other community leaders said the refusal by ICE officials to comment has frustrated efforts to calm fears.

After people whispered false rumors about immigration arrests at Saturday's Cinco de Mayo celebration in downtown Waterloo, de Gomez took to the air on Radio La Buena, a Spanish-language radio station in Cedar Falls, to give people the latest news.

"It's very distressing sometimes because you don't know what to tell people," she said. "The thing I'm concerned about is that the rumors start getting crazy and it causes panic."

The Rev. Jose Comparan, who leads the Hispanic ministry at Queen of Peace Catholic Church, said he first heard rumors of an immigration raid a few weeks ago. People told him workers were fired from the Tyson meatpacking plant in Waterloo because they lacked proper documentation, and they assumed a raid would soon follow.

Grey, the UNI professor, said when companies know a raid is coming, they often will fully cooperate with federal authorities to avoid prosecution. He has heard "persistent rumors" that companies engage in pre-emptive firings to avoid legal trouble, but said he has no proof of such actions.

Tyson Foods spokesman Gary Mickelson would not comment on the alleged firings. In an e-mailed statement, he said the company has "zero tolerance" for unauthorized workers.

"If the worker is unable to resolve any discrepancies in their documentation, then they are released from employment," he said.

Alexandra Frazier, a case worker at El Centro Latinoamericano, helped two natives of the Dominican Republic after they said they were let go.

Francisco Vilorio Correa, 60, and Tinidad Noemi del Carmen, 30, said Tyson Foods fired them on April 23 because, despite their best efforts, they couldn't prove their legal status to the company's satisfaction. They estimated they were two of more than 20 people fired that day.

The pair said they double-checked their documents with a local Social Security office and presented them to Tyson again two days later in hopes of returning to the production line. But management, they said, told them their documents - a Social Security number, a state-issued ID and a passport - were not sufficient to prove their legal status.

In an e-mailed statement, Mickelson did not confirm or deny the workers' story, and did not comment on the timing of the alleged firings.

"As part of our best management practices we regularly audit the work authorization documents we have on file, however, it would not be appropriate for us to comment further since we consider individual personnel matters confidential," he said.

Contact Jens Manuel Krogstad at (319) 291-1580 or jens.krogstad@wcfcourier.com.