The New York City mayor's office is calling it the "largest seizure of illegal guns in city history."

The 10-month undercover investigation by the New York Police Department hauled in 254 firearms and led to 19 arrests. Authorities singled out two suspects, Walter Walker of Sanford, N.C., and Earl Campbell of Rock Hill, S.C., who have been charged with smuggling the guns in their luggage up the coast on discount buses headed to New York City's Chinatown.

The guns were sold to the same Brooklyn-based gun dealer, resulting in illegal sales totaling around $160,000. Thanks to Bloomberg's strict gun laws, firearms can fetch three times as much money in New York City as they can in states like North Carolina and South Carolina.

The NYPD initially caught wind of the trafficking ring during an unrelated drug bust, eventually discovering other clues like photos of the guns allegedly posted on Instagram by an aspiring hip-hop artist who was working with Walker.

Mayor Michael Bloomberg had plenty of praise for the NYPD, and he also had some harsh words for the home states of the two alleged gunrunners. "New York is the safest big city in the nation, but year after year, illegal guns flow into our city from states that don't have common-sense laws that keep guns out of the hands of criminals,” he told reporters.

Other city officials, like Criminal Justice Coordinator John Feinblatt, echoed the mayor's statement, saying, "What remains abundantly clear is what happens in other states can have lethal consequences on our streets too."

This isn't the first time that New York City has blamed other states for the guns on its streets.

In July, Bloomberg cited data from the Bureau of Alcohol, Tobacco, Firearms and Explosives to claim that in 2011, 90 percent of the 2,433 traceable guns used in crimes in the city came from outside of New York state — an increase from 86 percent in 2010. His office identified the top sources of out-of-state guns:

The billionaire mayor isn't all talk. In 2006, he spent $3 million of his own money to start Mayor Against Illegal Guns, which has since run ads against politicians who oppose gun control measures.

Not everyone approves of Bloomberg's methods. "They're not just against illegal guns, they're against all guns," Sioux City Mayor Bob Scott, who left the group in July, told reporters. And National Review suggested that Bloomberg, a former Republican turned Independent, change the name of his organization to "Liberal Mayors Against the Second Amendment."

Despite opposition from conservatives and groups like the National Rifle Association, Bloomberg was adamant, even defiant, when defending his push for stricter gun control laws across the country. "To those who say 'stay out of our state,' our answer is: We'd love to, just as soon as you stop letting guns seep into the black market and get in the hands of criminals who murder our citizens," he told The Wall Street Journal.