I hung-out there, for about an hour. I was as interested in the process, as anything else. The line of people waiting, gun(s) in hand, was a block long, and until they got to the FRONT of the line, nobody checked to see if any of the guns were loaded!
From the looks of most of the guns being turned-in, I'd say they weren't taken "off the street", so much as out of the barn. Mostly rimfire bolt-guns, though there was some interesting stuff.
While the whole idea of a buy-BACK is ridiculous, this one at least had a little thought behind it. They claimed they would try to return guns that were determined to be stolen, and they apparently were not going to destroy guns which had been identified as rare or collectible, though I don't know who was responsible for making that call, or who would have access to any resulting sales.
I've seen some reports that made it sound like there was "a table" where people could get cash for their guns, if they thought they wanted more than $100, and in the form of money rather than a gift card, but I'd say the number of people actively trying to buy guns before they went behind the "do not cross" tape, was close to twenty, at noon.
I had some money in my pocket, but I should have shown up late, rather than early, to catch the people who came out for a gift card but got there too late; those folks might take $50 cash, rather than carry the gun home.