Brandon and Brian Beharry should have been getting ready for the first day of school in Long Branch on Thursday. Instead, they are victims of a mysterious fire that took their lives.

FIrefighters and neighbors at a fire in Long Branch (CBS New York)

The 7-year-old and 4-year-old were killed along with their mother Amanda Morris and father Lyndon “Shane” Beharry in a fire inside their Long Branch early Wednesday morning the Monmouth County Prosecutor's Office terms as "not accidental" and a possible murder-suicide.  Public Information Officer Charles Webster in a statement says "the cause and manner of death for each of the victims will be determined by a post-mortem examination by the medical examiner’s office."

Neighbor Confesor Perez tells the Asbury Park Press he heard a loud boom and then a second bang he thought were gunshots just before the fire broke out around midnight on Tuesday night. Other neighbors heard it and came outside to see smoke and flames in the Beharry home

“They tried to get upstairs to the second floor. The house was already fully involved,” Public Safety Director Jason Roebuck told CBS New York about neighbors' efforts to help. “They couldn’t make their way past the smoke and fire.”

NBC 4 New York cites a neighbor saying Amanda Morris and Shane Beharry had an argument  in their front yard on Saturday shortly after returning from a Florida family vacation, but the neighbor wasn't sure what it was about. CBS New York cites unnamed friends claiming Amanda Morris, Shane Beharry's girlfriend, was threatening to leave him with the children.

Friends and neighbors trying to wrap their heads around the family's death brought balloons, candles and flowers to an impromptu memorial in front of the family's Joline Avenue home Wednesday night.

"This is one (case) that is totally incomprehensible,” Long Branch Mayor Adam Schneidertold the Asbury Park Press. “None of this is making any sense to any of us.”

Co-workers at the Long Branch Public Works, where Shane Beharry worked for 16 years told CBS New Yorkthat his life revolved around his boys and described him as a family man.

"We are all mourning the loss of our children today," Long Branch superintendent of  schools Michael Salvatore said in a written statement to NBC 4 New York. "While thousands of children are preparing to enter schools tomorrow, our hears and prayers will be with the children that didn't have the opportunity."

The Monmouth County Prosecutor's Office has asked anyone with information that could help the investigation to call 800-533-7443 or Long Branch Police at 732-222-1000.