High-tech surveillance greets junior hockey fans in Tri-Cities, Washington

It's also a crucial front in the Department of Homeland Security's war against suicide bombers.

During the tests of crowd surveillance technology, an array of surveillance cameras, infrared cameras, and millimeter-wave radar is used to scan fans of the Western Hockey League's Tri-City Americans, who play at the town's 6,000-seat Toyota Center.

Software algorithms -- complex image-processing formulas called video analytics -- instantly analyze the data and images.

Privacy advocates and critics of Homeland Security spending object to the idea of training all that high technology on law-abiding citizens. But hockey fans in this languid Columbia River town near Oregon don't seem to mind being test subjects.

"We're trying to figure out how to protect large venues from terrorist attacks," said Nicholas Lombardo, project manager for Pacific Northwest National Laboratory, one of nine Department of Energy national laboratories. The lab, in nearby Richland, is coordinating the testing, which initially focuses on pedestrians and will expand to include vehicles in coming years.

In general, the security technology is looking for three things: suicide bombers on foot, suspicious packages left behind and vehicles that may carry explosives. The goal is to identify assailants long before they reach fixed points, like box office windows or bag-search areas.

By pushing detection to 500 feet earlier than traditional checkpoints, the system is able to start tracking people approaching the building from a distance.

Another goal is to inspect every person in a crowd of thousands -- probing for heat generated by concealed explosives, scanning for weapons and analyzing odd behavior.

Video streams of crowd movements are fed into computers. If the program detects someone running away from the event or loitering or leaving a package behind, the behavior is highlighted for an operator.

The operators at the Kennewick arena are local law enforcement officers hired to run the equipment from inside a nearby trailer. Watching a wall of flat screens, they can focus all of the different types of cameras on a single person, then decide whether to stop and interrogate the person.