Various terms are used to describe such incidents—armed assault, armed attack, intrusion, deadly force incident, active shooter, mass casualty incident, and targeted act of violence to name a few.
An active shooter is an individual actively engaged in killing or attempting to kill people in a confined space or other populated area, most often using firearms and following no pattern or method in the selection of victims.
Targeted violence refers to any incident of violence where the location was deliberately selected and not simply a random site of opportunity and where the perpetrator selected a target before the incident. For example, incidents where the attack “just happened to occur” at that location, such as consequences of gang or drug activity, would not be included. 
