What if a gunman stormed the University of Colorado at Colorado Springs, shooting at random? What if someone had a dirty bomb, or released a toxic chemical?
Those scenarios will play out on campus Friday in a wide-ranging exercise designed to test the emergency-response system in El Paso County, Colo.
More than 300 people will participate, including first responders and volunteers who will pretend to be victims and panicked onlookers.
The goal is to see how well emergency workers from a variety of local agencies work together in confronting several violent attacks.
"The key will be how all our agencies get together for a common goal, keeping in mind they may be responsible for different kinds of tasks," said Colorado Springs Fire Department spokeswoman Lt. Julie Stone. Law enforcement officers from the El Paso County Sheriff's Office, and Colorado Springs and university police departments will also be involved.
Their ability to coordinate the exchange of information and keep lines of communication open to the public will also be tested in the exercise, which was designed by the South Central All-Hazard Region, encompassing El Paso, Teller, Park, Lake and Chaffee counties.
The test is scheduled for 9 a.m. to 5. p.m. It will be the last in a series of three tests funded by a $70,000 grant from the federal Department of Homeland Security.
Last summer, Colorado Springs police and university police practiced how to breach buildings in case of an "active shooter" such as those at Columbine High School and Virginia Tech in Blacksburg, Va.
In January, the agencies used table-top models to devise a coordinated response to a school shooting that also includes an improvised explosive device and toxic chemicals.
In Friday's exercise the agencies will put those experiences to practice in real time, with live-action participants. How and where the disasters unfold will be left a mystery until then.
Each phase of the exercise will be scored by a group of evaluators, and an "after-action report" evaluating the collective response will be ready in 30 to 60 days.
The exercise was planned for the university's spring break. Remaining students, faculty and staff were alerted with posters and notices from university police.