From what we can gather, after the girls had lain down on Donald Avenue they fell asleep, and did so not far from an intersection. When a car turned onto Donald Ave from the crossroad, it ran over the girls. Turns out that car contained three cousins of one of the injured girls, with one of them, a 19-year-old male, driving.
The good news is that the girls were airlifted to the hospital and are in stable condition. The bad news is what their parents have in store for them when they're recovered and home. Check out the news segment on WTAE Pittsburgh for the full report.