NEW YORK (AP) — New York Mayor Michael Bloomberg calls it a "deadly serious problem."

The city has released a report describing a sting at gun shows in Tennessee, Ohio and Nevada in which officials secretly videotaped dozens of purportedly illegal purchases.

Unlike New York, the states haven't closed the "gun show loophole," which allows private unlicensed dealers to sell weapons at gun shows without conducting background checks.

But federal law does bar the sellers from selling guns to people they have reason to believe would fail a background check. The city says 19 out of 30 sellers broke the law in the operation, in which undercover buyers suggested they wouldn't pass a background check. Two assault rifles and 20 semiautomatic handguns were bought.

According to the city's report, some sellers said things like "I couldn't pass one either," or "I don't care."

Bloomberg says the report shows how pervasive the problem is.