National Guard units from Colorado, New Mexico and Utah are training in the Denver area over the next five days on how to respond to a terrorist attack.
The Colorado National Guard said the exercise started Thursday and run through Tuesday.
Officials said some of the training will occur at Denver International Airport, Community College of Aurora, Castlewood Canyon State Park, University Hospital and Skyridge Hospital.
Officials said the training scenario calls for mock attacks similar to the ones in Paris in November 2015.