Last evening, transferring through Pittsburgh, saw a prop (looked like a Dash-8) on the runway waiting for a tow - couple of fire trucks and people in those fire space suits around the plane. Looked like the crew was walking around on the ground - somebody had brought stairs to the side of the plane. Out of idle curiosity, anybody know what happened?

Apparently there was ET onboard :)

Don't see any mention in the P-G of anything. Possibly it was a drill of some sort. Did you see any passengers evacuating?