COLORADO SPRINGS, Colo. -- Destroying key communication towers and spreading poison gas across a college campus are among the scenarios authorities must prepare for. They simulated those scenarios Wednesday in the Rockhurst neighborhood above the UCCS campus.

Emergency vehicles and personnel filled the neighborhood for the seventh annual Coalition Warrior Interoperability Demonstration (CWID). Northcom, the federal agency responsible for homeland defense and located in Colorado Springs, conducts the training in selected cities around the world.

Colorado Springs' police and fire departments, along with UCCS Public Safety, participated in the drill with Northcom.

As part of the scenarios, terrorists were arrested, emergency personnel were decontaminated and a balloon carrying temporary communication equipment rose into the sky. Neighbors were notified of the exercise in advance.

Authorities said the biggest challenge they face is getting temporary communication running quickly, because it can take as long as several days to order the necessary equipment if a city doesn't already have it. Another challenge, they said, is cities with tight budgets -- like Colorado Springs -- being able to afford expensive technology. One official said state and federal funds likely would be available if a situation is declared an emergency.

The exercise ends late Wednesday with an initial evaluation. A more in-depth evaluation is expected this fall.