Were loosed (eluqhsan). First aorist (ingressive) passive indicative of luw, "were let loose." Which had been prepared (oi htoimasmenoi). Perfect passive articular participle of etoimazw, to make ready (etoimo), in a state of readiness prepared by God ( Deuteronomy 12:6 ; Deuteronomy 16:12 ; Matthew 25:34 ). For the hour and day and month and year (ei thn wran kai hmeran kai mhna kai eniauton). For this use of ei with htoimasmenon see 2 Timothy 2:21 . All preparation over, the angels are waiting for the signal to begin. That they should kill (ina apokteinwsin). The same idiom in verse 2 Timothy 5 about the fifth trumpet, which brought torture. This one brings death.