INDIANAPOLIS — Indianapolis homicide detectives are investigating the shooting death of a 17-year-old outside a southwest side apartment building where neighbors said a party was going on.

Authorities identified the teenager as Xavier Fairley. A friend of Fairley said he was due to graduate high school this week.

Police were called shortly after midnight to the apartments in the 6700 block of Twig Place.

Neighbors, who wished to remain anonymous, said a party had been going on in one of the units in the hours leading up to the shooting.

“When the gunshots did go off, it was quiet and then there was a little rumbling of voices,” said one woman. “There was definitely some heated words going on, but only one person speaking, and after that the three shots went off, and that was it.

“It was definitely a threat,” she recalled. “They said, the other person better not do whatever they did again and called him a bad name and then shot him.”

A friend of Fairley said that he had stepped outside to relieve himself when he was shot.

“There was a lot of young kids still, and they were across the street,” said another neighbor who witnessed the aftermath. “There was a girl was a little bit distraught, and there was another kid sitting with his head in his hands, and they stayed there for quite some time.”

Fairley was found on the bank of a retention pond and rushed to the hospital. He is at least the 15th teenager to die of gun violence in Indianapolis this year.

“Somebody told me this morning that this kind of stuff happens everywhere,” said one neighbor. “Well, why does it happen everywhere? Because it is not right. A 17-year-old’s life was taken, and that’s the son of somebody’s mother, and I have an issue with that.”

“I mean, it’s like, wow, you can’t believe how people react to stuff,” said another neighbor. “I thought it was a great neighborhood.”

Almost 20% of Indianapolis’ more than 80 homicide victims this year have been people under the age of 20.