(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.

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.

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