As a fast-moving fire raged inside a Shirley home, neighbors rushed to help the family trapped inside, only to be repelled by the intense heat.
Minutes later, firefighters did all they could to save the victims -- a mother and her three young children. But it was too late.
Brookhaven Town Supervisor Edward Romaine said firefighters at the scene late Friday night were in tears afterward.
"They had never seen anything so horrific," he said Saturday.
As flames filled the front of the single-story home on Hollywood Drive, police said the mother rushed to her 2-year-old twins' shared bedroom in the back of the house and pulled one from a crib. She was trying to save the second child when she was overcome by smoke, police said.
Firefighters found Jennifer McCusker, 41, in the bedroom clutching one of her children, police said. The victims were treated at the scene and later pronounced dead at Brookhaven Memorial Hospital Medical Center in East Patchogue.
It was the deadliest blaze on Long Island since four people died in an arson fire in Lawrence in 2009.
A high-ranking fire official, one of the first at the scene in Shirley, called it "the saddest thing I have ever seen . . . To see the life leaving those little babies was . . . horrible."
"All the kids came out of the house already in bad shape," said the official, who spoke on condition of anonymity because he was not authorized to discuss the case publicly. "We tried like hell to save them and their mother. We really did."
Grief swept the close-knit neighborhood as news spread that McCusker and her children -- Aidan Tarbell, 7, and twins Ava Jane and Brendan Mistretta -- had died.
The cause of the fire is under investigation, said Det. Lt. Jack Fitzpatrick, commander of the Suffolk homicide squad.
The fire appeared to have been sparked accidentally, said Brookhaven Town chief fire marshal Chris Mehrman. No further details were available. The police arson squad is assisting in the investigation.
Neighbors called 911 at 10:15 p.m., and firefighters had the blaze under control about 40 minutes later, police said. Fire crews from Mastic Beach, Mastic, Brookhaven and Center Moriches responded.
Witnesses said two residents trained as first responders -- an off-duty firefighter and a paramedic -- tried to enter the home but the fire was too intense.
"I heard loud popping noises and I came outside, and the house was engulfed in flames," said Ruthann Krafve, a neighbor and mother of the would-be rescuers. "It was pouring out the windows, out the sides."
Investigators believe the fire started in the front living room. Aidan was found in an adjoining bedroom.
"Aidan, Brendan and Ava were the best three kids that any father could hope for," the twins' distraught father, Peter Mistretta, said at the scene. "Jenni loved me no matter what. She was a beautiful mother, she was my best friend."
Aidan's father, Joseph Tarbell, 47, who lived in the basement of the home but wasn't there during the fire, posted on his Facebook page: "Heaven got 4 beautiful angels . . . Jennifer Brendan Eva and my Beautiful Son Aidan. I miss you my son my life will never be the same without you."
The Suffolk medical examiner's office will conduct autopsies to determine the cause of death.
The house appeared to have an illegal basement apartment, though it did not appear that unit played a role in the fire, Romaine said.
Relatives said McCusker worked for a health insurance company, and Aidan was a student at Hobart Elementary School.
James Montalto, a spokesman for the William Floyd school district, said grief counselors will be available to speak with students when school resumes Tuesday.
Krafve said McCusker grew up in the house in the close-knit, working-class neighborhood. She chose to raise her own children there as well.
"She was a good mom," Krafve said. "She loved her kids."
On Saturday, neighbors set up a makeshift memorial with photographs, flowers, scooters and teddy bears in front of the blackened home.
Said Mistretta, the twins' father: "Hug your kids . . . because you never know when they could be taken from you."
With Candice Ferrette, Carl MacGowan and Ted Phillips