According to the Los Angeles Police Department, the shooting was reported about 10:45 p.m. at a house in the 13400 block of Rangoon Street, near Canterbury Avenue.
News video showed LAPD officers and firefighter-paramedics arriving to a chaotic scene at the home.
A 17-year-old boy with multiple gunshot wounds was seen lying on the floor of the garage, where he was pronounced dead. Investigators initially gave his age as 16. He was not immediately identified.
Two other victims -- a 17-year-old boy and a 19-year-old man -- were wounded. An ambulance transported the younger survivor to a hospital where he was listed in stable condition. The 19-year-old transported himself to the medical center.
Both of those patients were later released from the hospital, police said.
"The investigation revealed that the victim attended a party at a residence and became involved in an altercation with the suspect," the LAPD said in a statement. "During the altercation, the suspect produced a handgun and shot the victim multiple times."
The male shooter ran to a dark-colored vehicle and got in, along with another male and a female, authorities said. The trio then drove away from the scene.
A detailed description of the gunman was not available.
Anyone with information about the shooting is asked to call Detective Steve Castro of the LAPD Valley Bureau's Homicide Division at (818) 374-1925.