A Monmouth County teenager is facing murder charges after he allegedly opened fire on his family with a semi-automatic rifle, county officials say.

Officials say that Long Branch police were called to 635 Wall Street New Year’s Eve around 11:45 p.m. for reports of gunfire. When officers arrived the 16-year-old suspect surrendered. Four people inside the home were dead.

The suspect’s name has not been released due to his age.

Officials said that the gun used in the killings was legally registered to a member of the household. Authorities did not say if the gun was secured prior to the shooting.

The victims have been identified as the suspect's father, Steven Kologi, 44; mother Linda Kologi, 42; sister Brittany Kologi, 18; and family acquaintance, Mary Schultz, 70. The teen’s 20-year-old brother and grandfather were able to escape the attack. Monmouth County Prosecutor Christopher Gramiccioni says that he does not believe that they were target.

Friends of the family tell News 12 New Jersey that the teen may have had a developmental disorder. They say that the teen usually kept to himself, but there was never any indication that the boy was violent.

“That's why I'm in shock. I'm in complete shock of all of this,” says family friend Ronnie Pacheco. “It just doesn't make any sense. At all.”

Friends of the victims gathered near the family’s home to offer condolences. Victoria Villanueva was friends with Brittany Kologi and worked with her at a local ice cream shop.

"I can't even fathom, I can't wrap my head around this...and what they're going through,” Villanueva says.

Villanueva says that she and another friend attempted to place flowers by the family's home but were turned away by police because it's an active crime scene.

The 16-year-old is expected to be arraigned Tuesday. Prosecutors did not yet say if he would be charged as an adult or as a juvenile.