During the early moments of the shooting and chase near the Capitol Building in Washington D.C a "shelter in place" order was issued by Capitol Police. What does that mean exactly?

Police close in on the U.S. Capitol as people run for cover after initial reports of a shooting (Alex Wong/Getty Images)

According to the Centers for Disease Control's emergency preparedness website page, it means you should "take immediate shelter where you are—at home, work, school, or in between."

The CDC says you can prepare ahead of time at home by choosing a room in advance for your shelter. The best room, according to the CDC,  is one with as few windows and doors as possible. A large room, preferably with a water supply, is desirable—something like a master bedroom that is connected to a bathroom.

At work, everyone should be assigned a task or responsibility ahead of time to perform when a shelter in place order is issued.