Fifteen days after the shooting rampage in Tucson that left six people dead and another 13 wounded by gunfire, New York City investigators went to a Phoenix gun show and were able to purchase a handgun and extended magazine like those used in the attack even though federal law says they should not have been able to buy them, Mayor Michael Bloomberg announced today.

According to a statement issued by Bloomberg’s office:

“The investigation proves on video how easy it is to obtain firearms with high capacity magazines at gun shows, even for those who tell sellers that they probably couldn’t pass a background check.

“A Glock pistol with a 33-round extended magazine, like the weapon used in Tucson, was legally purchased with no background check — exposing a dangerous gap in our existing federal gun laws.

“Two other semi-automatic pistols were purchased with no checks even after sellers were told by undercover buyers that they probably could not pass a background check; under federal law the sellers should have stopped the sale.”

Bloomberg, as NPR’s Liz Halloran has previously reported, has been waging a high-profile campaign against illegal sales of firearms at gun shows — in large part because New York officials say many of the guns end up being used in crimes committed in their city. In 2009, the “Gun Show Undercover” campaign he launched conducted “stings” at shows in three states.

The Jan. 8 attack in Tucson happened at a strip mall during a meet-and-greet event Rep. Gabrielle Giffords (D-AZ) was holding with constituents. She was shot in the head and is now at a rehabilitation center in Houston.

Here is the video Bloomberg’s campaign put together about what they did at the Jan. 23 gun show in Phoenix: Copyright 2011 National Public Radio. To see more, visit http://www.npr.org/.