Same girl in both photos
+++++++++++++++
I think you are right.
But hard to see how she escaped the explosion unless she left her position right after the photo was taken. Could be she saw the backpack and got spooked.
Hmm, now I just noticed that the girl in the first pic has white shorts and the one in the second has black shorts, and the 3 girls in the first pic all have Nike running shows like the girl in the 2nd. This may have been a team of Tufts supporters or runners? Now I’m not feeling so well as those 1st pic girls may well have been caught in the blast.