Police officers are trained to not be too 'quick on the trigger'. [=eager to fire a gun]
The timer was set to 'trigger' the bomb in exactly one hour.
The faulty wire was the 'trigger for' the explosion.
(..) -We're looking for fuel. LEN: The dark season's coming. We only got enough for ourselves. You point that gun at somebody, you better be ready to pull the trigger. VIRGINIA: Put your guns down, everyone. Look, we just came to find the Resistance, that's all. LEN: (..)2009 Terminator Salvation
(..) You're obviously not a Resistance fighter, so take it off. Take it off! You point a gun at someone... ...you'd better be ready to pull the trigger. Now, I'm gonna ask you one more time. -What the hell was that thing? -Terminator. T-. (..)2009 Terminator Salvation