IA/RD tactics are recommended for situations in which one or more people are engaged in ongoing aggressive, deadly behavior, such as occurred at Columbine High School in Littleton, CO, in April 1999. Shortly after the Columbine attack, the SWAT team leaders of the Los Angeles Police Department met to discuss how first-responder patrol officers should approach a similar scenario. The consensus of the SWAT leaders was that the first-responding officers--ideally four officers--should enter the location as a contact team using a diamond formation. The main objective of the team would be to stop the assailant's deadly behavior. Additional officers could be used as a second contact team, if needed, or as a rescue team to help with the removal of victims in need of emergency medical care. This strategy and tactics evolved to become the core of what is now called "Immediate Action/ Rapid Deployment." Under the diamond formation, the "designated cover officer" takes the point position in the front of the diamond. This officer generally carries a shotgun. The team leader assumes a position to the left of right flank of the diamond, and the general-purpose officer is positioned opposite the team leader's flank. The assistant team leader assumes the rear guard position at the back point of the diamond. This formation allows for 360-degree coverage and surveillance while the team moves in an aggressive, controlled, and precise manner. Other issues discussed are the use of deadly force, use of cover fire, lag time, and encountering explosive devices. Fire department and tactical emergency medical services are also discussed. Procedures when the SWAT team arrives are discussed. 7 diagrams