LONG BRANCH, N.J. (CBSNewYork/AP) — A 16-year-old boy is in custody after authorities said his parents, sister and a family friend were found shot to death inside a Long Branch home.

Monmouth County Prosecutor Chris Gramiccioni said Monday the teenager is expected to face four counts of murder and other charges in the shooting deaths of his parents, Steven and Linda Kologi, 44 and 42 respectively, his 18-year-old sister, Brittany, and 70-year-old Mary Schultz, who lived with the family.

“It’s a terribly tragic incident,” Gramiccioni said.

Police said the family New Year’s Eve gathering turned into a quadruple homicide around 11:45 p.m. Sunday inside the multi-family home on Wall Street. Neighbors said they heard gunshots from down the street.

“I came outside last night about midnight to look and see what’s going on,” said neighbor James Roskowinski. “I was saying, ‘I’m pretty sure that was gunshots.’ Looked outside, before you know it cop down here, cop down there lined up around the street.”

When officers arrived, authorities said they found the four victims dead inside. The prosecutor said the grandfather and a brother were in the house but unharmed.

The teen was taken into custody without incident and police said the shooting appears to stem from a domestic incident.

Family friend Chris Grico said Steven Kologi coached T-ball.

“Great guy, family man,” he told WCBS 880’s Sean Adams.

Walter Montelione is Linda’s cousin and spoke exclusively to CBS2’s Lisa Rozner through tears by phone.

“The Kologis were very caring, loving people and always looking to do fun things with their kids,” he said. “He was a good kid. He was, a little you know, slow with learning disabilities but he knows right from wrong.”

A possible motive for the shooting has not been disclosed. Gramiccioni said the rifle used in the shooting was legally registered to a resident of the house.

Gramiccioni said charges are expected to be filed later Monday. The teen is expected to make an initial court appearance on Tuesday.

Anyone with information is asked to call Detective Andrea Tozzi, of the Monmouth County Prosecutor’s Office at 800-533-7443, or Detective Michael Verdadiero of the Long Branch Police Department at 732-222-1000.

(© Copyright 2018 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)