Gangs in New York are heavily armed. Reuters

New York gang members have been arrested in connection with three murders after police monitored them on Facebook and Twitter.

Police Commissioner Raymond Kelly said that the 25 members of the Wave Gang and 18 members of rivals Hoodstarz regularly clashed in bloody shootouts.

They then went on to brag about the clashes on social media sites, which the police monitored. Some of the gang members were as young as 15.

They were charged for an array of crimes including murder, assault, robbery and possession of weapons.

Brooklyn's district attorney Charles Hynes said the fight against gang culture would spread across New York.

"We know who you are. We know how you operate. We are coming after you next," he said.