Army and Air National Guard members assigned to the Ohio National Guard's Chemical, Biological, Radiological, Nuclear Enhanced Response Force Package (CERFP) practice extracting victims trapped in the rubble of a collapsed building during Vigilant Guard, a joint military and civilian training exercise simulating the detonation of an improvised nuclear device in a major metropolitan area May 10. Rubble and debris pose a challenge for the service members conducting operations at Muscatatuk Urban Training Center near North Vernon, Ind.