Law enforcement authorities on Monday said they halted two loosely organized gun-smuggling operations and confiscated more than 250 firearms -- which the New York Police Department claims is the largest such seizure in the agency's history.

The operation involved a single undercover officer who purchased 254 guns in 45 separate transactions, authorities said. The weapons were transported from two southern states through means including low-cost buses to Manhattan’s Chinatown, Police Commissioner Raymond Kelly and Mayor Michael Bloomberg said.

The seized firearms vary from .22 caliber pistols to semi-automatic rifles. "Among the guns sold were a fully automatic Cobray 9 millimeter machine gun with a 30-round high-capacity magazine" and three Intertec 9 pistols with flash suppressors and magazines that hold 30 or more rounds, according to a news release.

In all, police arrested 19 people in New York, North Carolina and South Carolina, including Walter Walker and Earl Campbell, who allegedly smuggled the guns to New York, authorities said.