Wiktionary
vb. 1 (context idiomatic US English) To take hasty, immediate action with serious consequences, without first adequately investigating the situation. 2 (context idiomatic US English) To act boldly.
Usage examples of "shoot first and ask questions later".
Those fuckers are loaded for bear and look like the kind who'd shoot first and ask questions later.
If they found her while she was cutting Fergusson to pieces, they'd probably shoot first and ask questions later.
You'll find things are different out here, and there's a lot of folks who will shoot first and ask questions later, if they have any to ask.
Even if you get out, they can stick you on the most wanted list of fifty nations as the man who murdered the Queen and stole the Crown Jewels, and the stupid shits in every law enforcement body in the world will shoot first and ask questions later.
I mean, hell, the closer we get to Hill's mansion, the less leeway the guards will give us before they decide to shoot first and ask questions later.
Count yourself lucky that I didn't shoot first and ask questions later.
The sailor was young and frightened and might shoot first and ask questions later.