(LOS ANGELES) — Investigators have been quiet about the events that led to the fatal shooting of an off-duty Los Angeles Police Department officer over the weekend, but sources with knowledge of the matter said he died after confronting a group of gang-affiliated vandals.Los Angeles Police Chief Michel Moore revealed that 24-year-old Juan Diaz had been shot and killed in an “act of senseless violence” early Saturday morning and asked for the community’s support in finding his killer.Moore did not share details about the circumstances surrounding his murder, but police sources told local news outlets, including ABC’s Los Angeles station KABC, that the young officer died after approaching a group of male graffiti artists.Diaz, who had been with the department for just two years, was eating at a taco stand with his girlfriend and her two brothers at around 1 a.m. when he noticed several young men defacing a property in LA’s Lincoln Heights neighborhood, a police source told KABC. The officer had ordered the men to stop when one of them pulled out a gun and began threatening him.The officer and his companions tried to avoid an altercation by getting into their vehicle and leaving, but the gunman opened fire, killing Diaz and injuring one the girlfriend’s brothers, the police source said.The shooter reportedly identified himself as a member of a gang whose territory included the area around the scene of the shooting, according to KABC.The police department declined to identify the surviving victim of the shooting and it did not offer details on their condition. Officials said they would provide more details as they become available.A description of the gunman was not available and no arrests had been made as of Sunday afternoon.Dozens of family members, friends and fellow officers gathered for a vigil at the LAPD’s headquarters on Saturday. The department tweeted images from the gathering late Saturday night, remembering him as a “dedicated public servant and Angeleno that put service to others above all else.””Tonight we gathered to honor a man who dedicated himself to our city — A man whose passion was LA,” the department said in a subsequent tweet. “There were hugs & tears—but we held our heads high as we paid tribute to his dedication to something greater than himself. Tonight our HQ Facility is proud to have Juan front & center.”The officer’s loved one and several members of the force — including Sgt. Manuel Hernandez, his police academy training officer — spoke at the vigil.”He grew up in a bad neighborhood, infested with gangs, yet he led a good life,” Hernandez said.”What we mainly want is for all of you guys to remember Juan for the goofball he was, the personality he was, always made someone smile,” Diaz’s sister, Anahi Diaz, added.Copyright © 2019, ABC Radio. All rights reserved.