active shooter

[ ak-tiv shoo-ter ]
/ ˈæk tɪv ˈʃu tər /

noun

a person who is presently using a gun to shoot people in a confined and populated area.

Origin of active shooter

First recorded in 1965–70
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019