"Large hail is pretty rare this close to the Front Range," said Knight, a senior scientist at the National Center for Atmospheric Research. "It's really pretty rare anywhere."
"There haven't been statements from overseas linking this to extremist groups outside the country — that is quite positive," said Charles Knight, lecturer in the Department of Policing, Intelligence and Counter Terrorism at Australia's Macquarie University. "The individual or individuals involved didn't kill early, which is part of the pattern of some recent international attacks. ... It seems to be shifting more into the model of a traditional hostage situation, rather than the sort of brutal attacks we've seen overseas."