I just rewatched it, and this is what I heard- (the one bit I can't hear properly, no matter how many times I rewind, I [ ]d.)

"Exterminieren! Exterminieren!"
"Halt! Sonst werden wir sie exterminieren! Sie sind jetzt [eingefangene?]" der Daleks!"
I'm thinking 'gefangene der Daleks' would make more sense to me, but it does sound like he says 'ein'...