The so-called gun show loophole which allows guns to be sold without a background check allowed private dealers to effectively hijack a weekend effort by Seattle police to get guns off the street.

Following the mass shooting at an elementary school in Connecticut last month, Seattle raised $120,000 to hold the first gun buyback effort in 20 years at a downtown parking lot on Saturday.

The plan was to trade gift cards for guns that would later be destroyed, but a number of dealers set up a mini-gun show just a block away in a effort to buy up the guns and keep them in circulation.

"I pay cash, I don't give Amazon gift cards," one dealer told a gun seller in video captured by KING.

"It's a historical firearm, I would hate to see it get destroyed," a buyer remarked to another gun owner. "I'll give you $100 cash for it."

"I would rather see it turned back into the gun community here and used to promote shooting sports," a dealer explained to KING.

Mason Vranish bought a rocket launcher off of a man who had come to trade it for a gift card, but police confiscated the weapon on the suspicion that it had been stolen from the U.S. military.

But Seattle Police Chief John Diaz suggested that program was a success overall because the $200 gift cards for assault weapons and the $100 gift cards for all other guns ran out before the day was over.

"I would prefer that they would not sell them [to dealers]," Diaz said of the private sales. "Some are looking at this as a money making operation. But I think that is very few of the people. Most people are here in the spirit of wanting to do something because of some of the tragedies that we’ve seen in our country and in our own city."

Washington state law does not require a background check to for firearm sales involving private sellers.

Watch this video from KING, broadcast Jan. 27, 2013.