NEW YORK - New York City Mayor Bill de Blasio on Tuesday announced indictment of six gun traffickers for selling illegal guns in the city and vows to step up efforts to combat gun violence.

According to the indictment, from approximately January 2014 to August 2015, the defendants sold a total of 74 guns, as well as ammunition, to an undercover New York Police Department (NYPD) detective.

Among them, two were each charged with criminal sale of a firearm in the first degree, as well as a number of other criminal possession of a weapon and conspiracy charges. Four others are each charged with conspiracy in the fourth degree, as well as additional serious felony charges related to the sale and possession of the illegal firearms.

"Anyone dealing in illegal guns in our city is up against the full force of government. Our message today is clear: if you're selling illegal firearms, we will find you," said de Blasio. "We are supporting this work in every way we can - from investing in anti-violence NYPD resources to adding millions for anti-gang efforts."

"We will continue pushing Washington to step up with real and meaningful action as well," he added.

The majority of sales took place in broad daylight in residential neighborhoods in Harlem and East Harlem, with seven of the 45 total transactions taking place in the Bronx, said New York Police Commissioner William Bratton. In total, the defendants received more than $52,000 as a result of the firearms purchases during the investigation.

The investigations in both cases were conducted jointly by the Manhattan District Attorney's Violent Criminal Enterprises Unit (VCEU) and the NYPD's Firearms Investigation Unit.

VCEU was created in 2010 to lead the efforts of the Manhattan District Attorney's Office in combating gun and gang violence, with a special focus on illegal firearms trafficking within New York City.

Since its formation, VCEU has brought 21 indictments against 64 gun traffickers operating between New York City and states including Virginia, North and South Carolina, Georgia, Ohio, New Jersey and Pennsylvania.