They were able to get past K9 and he escaped them before they could harm him. But they had found their way to it and started an attack on all of the other alternative timelines.

It was a small group of them, but it only takes a single Dalek to lay waste to an entire city. When they found us, it was only because they recognized me as... [ Her face twisted for that split second as she all but spat out the name: ] Unit 117 [ Before she regained her composure. ] ... were Narvin, Leela, and I able to survive their initial attack.