Armed officers in full battle gear will be scattered throughout the Bay Area this weekend, rescuing hostages, fighting bank robbers and quelling terrorism at the Oakland Airport, Lawrence Livermore Laboratory, the NASA Ames Research Center and 22 other high profile sites.

There will be the sound of gunfire and blasts — all part of Urban Shield, one of the biggest domestic terrorism drills in the country. The $1 million, two-day event begins Saturday and will test the training of 27 crack teams from throughout the state, elsewhere in the country and the world.

For the first time in the three-year history of the Alameda County Sheriff's Department-sponsored exercise, there will be a foreign team of officers taking part and international observers. An eight-member team representing the French National Police's Research, Assistance, Intervention, and Dissuasion unit will compete.

The exercise is a non-stop, 48-hour event meant to test a team's endurance and equipment in high stress situations such as shootouts, nuclear facility threats and airline hijackings. Each team is graded on their performances and at the end of the weekend, the top three teams are recognized. Amaury de Hauteclocque, chief of the French RAID team, said although there are opportunities in Europe to cross train with other countries' forces, there is nothing like Urban Shield, with 25 realistic scenarios at on-site locations.

"There are situations in the States we don't have in France, like a mass murder in a university," Hauteclocque said. "Fortunately we don't have them in France at this time, but we don't have a reason not to expect this to happen."

It's also an opportunity to improve relations between the two countries, he said.

RAID is a highly specialized team. Only one in 20 applicants are chosen to become a member, he said, adding that applicants must have five years experience with the French national police and must pass physical and psychological tests to be accepted.

The visiting team members were each chosen for being the best in specialties required for the exercise, Hauteclocque said.

Romulad Muller, police attache with the French Embassy in Washington, D.C., who accompanied the team, described them as the French "Dream Team." Members began training six months ago to learn how to combat the stress and fatigue they will face.

All 27 teams will run through each of the 25 scenarios. About 3,000 people are involved in the $1 million event, the cost of which is covered by Homeland Security grants and corporate sponsorships.

Alameda County Sheriff Greg Ahern said the excerise not only allows tactical teams to run through excerises it also allows them to practice disaster management coordination throughout the East Bay the Peninsula and the Silicon Valley.