NEW YORK (CBSNewYork) — More illegal weapons have been taken off New York City streets as a result of a year-long investigation that involved three separate undercover operations, officials said.

More than 150 guns, including pistols and assault rifles, were seized in Flatbush, Crown Heights and Bushwick, Police Commissioner Ray Kelly and Brooklyn District Attorney Charles Hynes announced Thursday.

1010 WINS’ Stan Brooks reports

Hynes said investigators also recovered a fully-automatic Sten gun with a 25-bullet magazine.

“A single pull of the trigger and this weapon fires 550 rounds per minute,” Hynes said. “You can imagine what the cops are up against with that thing on the street.”

Six of the guns were used to commit crimes in New York City, officials said. One of the weapons has been traced to a murder and two other shootings, officials said.

Another weapon turned out to be the service gun of a Pennsylvania State Trooper, officials said.  It was apparently stolen from his home during a burglary earlier this year, officials said.

Eleven suspects have been arrested and some are facing up to 25 years in prison if convicted of the most serious charges, 1010 WINS’ Stan Brooks reported.

“While New York City remains the safest large city in America, incidents of gun violence continue to plague our communities,” said Hynes. “The number of shootings in New York demonstrates clearly the need to keep illegal guns off the streets.”

The investigation is continuing.