It's not fully understood EXACTLY what was taken, but some reports (which stem from hearing police dispatch calls) mention multiple safes and possibly guns were taken.
I mean, what a TERRIBLE weekend for Gronk. The Pats lose a game they could've (and probably should've) won, and all the dude probably wants to do is just go home and zone out, and he gets home to a robbery scene? Bogus.
But seriously...WHO THE HELL ROBS GRONK?!