Your reaction and ability to communicate well in the event that you encounter a hostile intruder at the facility can mean saving lives. 
Respond in a Way That Keeps Everyone Safe

There are a few things you should consider carefully now so that if an incident does arise, you are fully prepared to protect yourself and your public entities.

If you know the hostile intruder’s location and you can confidently escape the area, this is your safest option. When this is not possible, immediately gather others into a room or office, lock the door and cover the windows. Above all, do not try to be a hero. Protect others as best you can and always put their safety ahead of yours.

Alert Authorities

Call 911 from an office phone or a cell phone. If the operators are overwhelmed with other calls, try calling local police or other emergency numbers, as well. Report your specific location, the number of people you have with you, any injuries and any information you might have about the intruder.
If you know what the assailant looks like, give the most accurate description possible. Try to stay as quiet as possible while doing this: silence all cell phones and keep everyone calm and out of sight, away from windows and doors.

Cooperate with Police

Do not leave your locked room until the police release you, and never enter into a hallway or open area. Before trying to rescue someone outside of the room, consider whether you might endanger the others in your group by doing so. When the first authorities arrive, they may not be able to tend immediately to any injured individuals—be patient and when you are able to speak with authorities, give them as much information about the situation as you can.

Be Prepared

Memorize the phone numbers of local authorities, or save them in your phone so they are easily accessible should an incident occur. Visualize the specific actions you would take in the event of an emergency so you are able to react quickly and without hesitation when lives are on the line.