Insomniax Gray S.W.A.T. Player Model Set

The Incident Commander shall request SWAT when at a barricaded or hostage incident when the suspect is probably armed; the suspect is believed to have been involved in a criminal act or is a significant threat to the lives and safety of the public and/or police; the suspect is in a position of advantage, affording cover and concealment or is contained in an open area and the presence or approach of police officers could precipitate an adverse reaction by the suspect; and, the suspect refuses to submit to arrest.

Source: http://www.lapdonline.org/inside_the_lapd/content_basic_view/848