"Lockdown" refers to a state or condition where people are required to stay inside a secured location, typically to ensure safety during an emergency or crisis situation. Full definition
The White House was briefly placed on lockdown in the wake of the shooting, which took place near 17th and E streets around 3:06 p.m. (nigeriapoliticsonline.com)
As of 2016, almost 95 percent of students in U.S. public schools practice some sort of lockdown drill according to the National Center for Education Statistics. (apmreports.org)
A «real and credible» threat caused Utica College to go in lockdown for hours yesterday, but no shots were fired on campus and no students were injured. (nystateofpolitics.com)