PELHAM, N.H. — A 2-year-old boy and an 8-month-old girl remained hospitalized for burns Wednesday after a large supply of fireworks exploded during a Fourth of July celebration here, engulfing the back deck of a home in flames.
Eleven people, including five children, were injured in the blast, which according to a relative ignited when a wayward firework accidentally struck the main supply. The detonation shook the neighborhood Tuesday evening and sent a fireball high into the air, neighbors and relatives said.
“The whole thing went off like a bomb,” said Skip Harrington, whose 2-year-old great-grandson sustained serious burns in the fire.
Harrington said the toddler, Ben, was near the fireworks when they exploded and was “completely engulfed in flames.” His mother, Jessica Bertini, rushed through the flames to rescue him, he said.
Ben was put into an induced coma Wednesday as doctors treated his burns, Harrington said. One firework lodged in his arm, and doctors told the family he would probably be hospitalized for at least a month, Harrington said.
The family is “just devastated,” he said. “He’s the nicest little boy.”
Bertini, 32, was burned but has been released from the hospital and is by Ben’s side, he said.
“She’s out of her mind” with worry, Harrington said.
A family spokesman told reporters Wednesday night that Ben was the only injured person who remained in the hospital.
Two children with “significant burns” were airlifted to the Shriners Hospitals for Children in Boston, officials said. The names of the injured were not released.
Investigators said that they have not determined the cause of the fire but that a large group had gathered at the home.
“Some fireworks were being discharged and there was a sudden explosion,” said Brian McCarthy of the Pelham police.
J. William Degnan, the state’s fire marshal, said he could not say what caused the explosion at this stage of the investigation. The fire started in the rear of the home, he said.
Most fireworks are legal in New Hampshire, but authorities are investigating whether any banned fireworks were involved.
Fire officials said they removed substantial quantities of fireworks from the two-story home, where owners Chris and Jeanne Pappathan have long hosted an elaborate display that draws dozens of onlookers.
William Troy had come to the top of his driveway with his family to see the fireworks when he saw a bright flash and heard an alarming boom from across the street.
“It was different,” said Troy, 71. “I’ve watched for the past 12 years and it was never like that. So I knew immediately something was wrong.”
Troy called the explosion a “freak accident.”
Jonathan LeBlanc, who lives next door, rushed out of his house when he heard the explosion and saw a barrage of fireworks crackle through the air.
“It was like a grand finale in the low horizon,” he said.
He heard screams over the bursts of fireworks, and saw someone sprawled on the lawn in obvious pain. Smoke billowed from the back of the house, and he began to spray the porch with a hose.
“It was just a very sad scene, traumatic to anyone who saw it,” he said. “From the sound of the pops, it seems like the fireworks all went off at the same time.”
Jim Midgley, the fire chief in this town of 13,000 on the Massachusetts line, said firefighters arrived minutes after the explosion to a chaotic scene: a street packed with cars and nervous residents, a smoldering house, and a host of injured.
Midgley, who said he was “not a fan” of fireworks, believes the Legislature should take a hard look at restricting them, and he preached caution.
“This is a tragedy that most likely could have been prevented had precautions been taken,” he said.
Degnan, the state’s fire marshal, said fireworks should be handled with care.
“They are explosives, and as you can see there was an explosion that injured quite a number of people,” he said. Viewers should stand at least 200 feet away from fireworks, he said.
Also on Tuesday, four teenagers in Rye, N.H., were injured when a glass bottle filled with lit sparklers exploded, authorities said. One of the victims, a boy, lost some of his fingers.
Stephen Coan, the fire marshal in Massachusetts, said the incident showed how dangerous and unpredictable fireworks can be.
“We typically see 10 or so fires and between eight and 10 documented incidents of injury over the holiday period,” he said.
In 2010, fireworks started an estimated 15,500 fires in the United States, and emergency rooms treated 8,600 people for fireworks-related injuries, according to the National Fire Protection Association. About 40 percent are under age 15. And on a typical July 4, far more fires are reported than on any other day.
Pelham authorities said they had never received any complaints about the family’s annual fireworks display.
Chris Pappathan works in insurance, and his wife, Jeanne, runs a hair salon, neighbors said.
Steven Jackson, a neighbor, said he watched the display many times and that the owners make sure there are no problems.
“It’s definitely not an act of carelessness, because Christopher has been very careful every year,” he said.
Travis Andersen of the Globe staff and Globe correspondent Colin A. Young contributed to this report. Peter Schworm can be reached at email@example.com. Follow him on Twitter @globepete.