DOWNTOWN BROOKLYN (WABC) -- A violent weekend is renewing community calls to end gun violence after 7 people were killed in 3 different boroughs. Investigators say they have their work cut out for them.So many times the 'don't snitch' mentality gets in the way of these investigations, but police say people in all of these communities need to come forward with information.Since Saturday, there has been one shooting in Manhattan, two in the Bronx, and two in Brooklyn.Early Sunday, police investigated a shooting that left three men dead outside a Downtown Brooklyn housing project.The shooting happened at about 2 a.m. in a walkway at the Raymond Ingersoll Houses just off Myrtle Avenue. A 43-year old man and a 39-year old man were shot in the head and pronounced dead at the scene. A 76-year old man was shot in the abdomen and died at Methodist Hospital. Police are questioning one person in the shootings, but so far there have been no arrests. Investigators say he then left the scene."It is in the best interest of our community that those who see anything step forward," says community activist Tony Herbert.Investigators are still searching for answers to bring justice, but can't bring loved ones back to life. Eyewitness News spoke with the brother of one of the victims who was too distraught to go on camera, but did say his brother died too young, and that gun violence has got to stop.