They're not usually this aggressive! This race keeps to themselves, usually underground, they don't bother anybody! The only time they act agressively is when they've been provoked, or are under distress. The portal must've dumped them here, and they're lost, confused, they don't know where they are. Hell, a lot of Displaced people might've acted the same way, had they not been quarantined in the military base when they first arrived, and given a chance to cool down, and had somebody explain to them what the hell's going on.
They're mildly telepathic, and have a sensitivity to time. If I bring the TARDIS to a central area and turn on the engine, even though the TARDIS' capacity to travel through time is disabled here, it ought to be enough to attract them. Then they can be captured.