Borrowed from the U.S. Department of Homeland Security
An "active shooter" is an individual who is engaged in killing or attempting to kill people in a confined and populated area; in most cases, active shooters use firearm(s) and there is no pattern or method to their selection of victims.
When an Active Shooter is in your vicinity, you must be prepared both mentally and physically to deal with the situation.
You have three options:
The first officers to arrive on scene will not stop to help the injured. Expect rescue teams to follow initial officers. These rescue teams will treat and remove the injured.
Once you have reached a safe location, you will likely be held in that area by law enforcement until the situation is under control, and all witnesses have been identified and questioned. DO NOT LEAVE THE AREA until law enforcement authorities have instructed you to do so.
When law enforcement arrives:
Information to provide to 911 operations:
For questions or additional assistance, contact:
Mount Horeb Police Department
400 Blue Mounds Street
Mt. Horeb, WI 53572
For more information from the U.S. Department of Homeland Security, their website can be found here.