DENVER -- Denver hospitals and medical personnel took part in a citywide emergency drill Tuesday.

The Mass Casualty Incident and Decontamination Drill was set up to prepare for a worst case scenario at the Democratic National Convention.

Information about the drill was not disclosed to hospitals ahead of time in order to make the most of the experience.

The drill, which began at 8 a.m., posed a possibility of 20,000 people exposed to a radioactive attack.

Ten hospitals throughout the city were alerted to an explosion inside the Pepsi Center.

Presbyterian St. Luke's set up a decontamination tent where scores of volunteer "victims" were treated.

Officials said they have to be ready for every possible scenario.