Bet it was dry ice + water in a 1 liter plastic bottle.
Happened here @ GA Tech.
We had a "suspicious package" near our building yesterday morning here in Da ATL, yo!
They closed down the streets, had a Cobra gunship flying around, bomb squad, Po Po, the works.
They saw wires in the package, blew it up onsite.
Surprise, no bomb.
It was someone's cell phone charger.