Just some of the 250 firearms obtained over the past year during the gun bust investigation. Twitter/NYPD news This week, NYPD announced the city's largest gun bust ever, seizing more than 250 illegal firearms and arresting 19 people, New York Daily News reports.

Two men were the gun runners for two separate operations, bringing weapons up from North and South Carolina. Seventeen others were part of their operations.

Authorities began the investigation one year ago. They were looking into an aspiring rapper in Brooklyn, Matthew Best, for narcotics when they realized he was selling weapons from his recording studio. Best's Instagram profile raised red flags after he posted images of guns and wads of cash to his account. YouTube videos also alluded to the weapon sales.

An undercover cop was allegedly able to buy 90 guns worth $75,000 from one of the runners, 23-year-old Earl Campbell, and 116 guns from 29-year-old Walter Walker worth $82,000.

Among the guns were high-capacity assault weapons and a fully-automatic machine gun.

During Monday's press conference, authorities said that the sellers only seemed to care about the money and didn't realize what kind of harm the gun sales could lead to. Special Narcotics Prosecutor Bridget Brennan described the ordeal as "both horrifying and comical."

Here are some of Best's Instagram images that aided the investigation.

Here's a video from the press conference announcing the gun bust.