Is there no risk of attack? Romney said there are always risks, but you minimize them and deal with them. He is confident enough in the Games security that he has invited 55 members of his family to the Games, and all are coming.

Low risk or not, federal officials are taking a cautious approach to potential terrorist attacks. Olympic athletes involved in military-sponsored training programs are no longer allowed to talk to the media unless approved by officials in Washington, D.C. The reason, said U.S. Army spokeswoman Harriet Rice, is security for the athletes.

One athlete, speaking without permission, told the Deseret News that government officials "fear we could be targeted by terrorists."

Catastrophic fears

Nationally, there is growing concern that the next wave of terrorist attacks will involve something even more horrific than the attacks on the World Trade Center and Pentagon, and that it will involve massive loss of human life.

Eisen said the real concern of the CIA and FBI is not so much a physical attack as it is a biological or chemical attack, perhaps by attacking interstate shipments of hazardous chemicals used by industry.

John Bromley, Union Pacific Railroad spokesman, said about 5 percent of its total rail shipments involves hazardous materials used mostly by industry.

Union Pacific has no plans to suspend interstate shipments of hazardous materials during the Games, and most of those materials will pass near downtown Salt Lake City.

The railroads all have their own security teams that guard against sabotage, and they have long-standing plans in place to deal with any release of hazardous materials. But it would be difficult, at best, to guard against sabotage along all of the thousands of miles of rail on all 34 trains that pass through Utah each day, Bromley said.

"We don't know if we will be doing anything different for the Olympics, but we are certainly discussing it internally," he said.

The potential for terror attacks extends far beyond the railroads. Every day, hundreds of semitrailer trucks carry hazardous materials through the heart of the city, mostly on I-15 and I-80. And four oil refineries straddle the Salt Lake-Davis County line, all with massive quantities of hazardous hydrofluoric acid used in the refining process.

Worst-case scenarios developed by the companies, local fire departments and the Environmental Protection Agency indicate that entire neighborhoods with tens of thousands of residents in Salt Lake City and south Davis County could be engulfed by toxic gases in the event emergency shutoff systems all fail and there is a massive release of chemicals.