(CNN)A New Jersey teenager is facing murder charges after allegedly using a semiautomatic rifle to kill his parents, sister and a family friend in the waning minutes of New Year's Eve, a prosecutor said.
NJ teen kills parents and sister on New Year's Eve, prosecutor says
Monmouth County Prosecutor Chris Gramiccioni called the crime a domestic incident in which the suspect's grandfather, a brother and another person managed to escape unharmed from a family home in Long Branch, a beachside city north of Asbury Park.
A family court judge on Wednesday retained the unidentified 16-year-old boy and issued a gag order prohibiting the release of additional information on the case, according to a Facebook post by the prosecutor's office.
The brother who escaped the killing spree -- named Steven, like his father -- on Tuesday remembered the victims on social media.
"My New Year's resolution is to be as great of a parent as my parents were to me," he wrote on Instagram.
"They were the greatest parents I could ask for. Never once was I without a hot meal or a roof over my head. They made sure Christmas came every year although they struggled financially. I cannot even describe the type of people they were so just believe me when I say how great they were."
He added, "I just wish I could tell all of them how much they meant to me and how much I truly loved each and every one of them because I didn't do that enough... Please remember to give the ones you love an extra kiss or I love you."
In the home, authorities found the bodies of Linda Kologi, 42; her husband, Steven Kologi, 44; their 18-year-old daughter, Brittany Kologi; and Mary Schultz, a 70-year-old friend who lived with the family.
"The case remains under investigation but the important thing I'd like the public ... to know is that we are investigating this and are confident that it's a domestic incident that's completely isolated," Gramiccioni told reporters.
There was no history of law enforcement calls to the home, Gramiccioni said.
The motive for the killings is unclear, he said.
A 911 caller from the home alerted authorities to the shootings at 11:43 p.m. Sunday, Gramiccioni said.
Investigators believe a "Century Arms semiautomatic rifle" was used in the crime. Gramiccioni said the weapon was "lawfully acquired" by a member of the family.
The weapon's magazine held up to 15 rounds, according to the prosecutor. The victims were shot multiple times.
Gramiccioni said the teen suspect faces murder and weapons charges.
The prosecutor is expected to recommend that he be charged as an adult, according to spokesman Chris Swendeman.