NEWTOWN, Conn. — Amid incalculable loss, this grieving town began the task of burying the young victims of Friday’s shooting rampage at Sandy Hook Elementary School, as investigators went about the exacting work of reconstructing the gunman’s life.
“We will go back to the date of his birth’’ to try to understand what motivated 20-year-old Adam Lanza to kill his mother and open fire at the school, said Lieutenant J. Paul Vance, a spokesman for the Connecticut State Police.
As the first two of a succession of funerals were held, authorities said the school, where 20 children and six adults were killed in one of the worst mass shootings in US history, would be closed indefinitely for a sprawling forensic examination.
Investigators seized “significant evidence” from the home where Lanza killed his mother before attacking the school. Lanza then turned the gun on himself as police descended.
Authorities said the forensic examination could take months.
“It’s a very painstaking process,” Vance said.
A day after President Obama addressed the town at the high school, vowing to use “whatever power this office holds” to prevent shooting massacres, authorities said there is no known connection between Lanza and the elementary school, rebutting earlier speculation and deepening the mystery around his motives.
Vance said two adults had been wounded in the attack and are being counted on to provide information about what they witnessed. He said investigators would be looking closely at “every aspect” of the weapons and ammunition used in the attack.
“We will look at every aspect of it from stem to stern,” he said. “Everything to do with all the weapons.”
Asked why such an extensive investigation was necessary when the perpetrator was known, Vance said that many people have “broken hearts” and deserve answers to “exactly why, and how, this tragedy occurred.”
“The answers are for the poor victims, the families, the people of Connecticut that need to know and see a clear picture as to exactly what happened here,” he said. “We’re going to do everything that it takes.”
In Fairfield, more than 100 mourners gathered for the funeral of Noah Pozner, a 6-year-old remembered as a bright, buoyant little boy who loved his family deeply.
After a private service at a two-story clapboard funeral home, mourners recalled a moving eulogy delivered by the boy’s mother, Veronique.
Outside the funeral home were flowers, teddy bears, white balloons, and a sign that read, “Our hearts are with you, Noah.”
Noah’s older brother, Michael, said he believed that Noah was “going to take up our cause” in heaven, one mourner said. Family tenderly recalled that the young boy was studious, at least most of the time, but also had a mischievous side that made him all the more endearing.
Most of all, they said, he was unabashedly close with his family.
“I love you,” his mother would tell him. “Not as much as I love you,” he would always reply.
Family fondly recalled the boy’s varying career aspirations. Some days, he wanted to become a doctor. Others, he proclaimed he wanted to be the manager of a taco factory, so he and his family could eat as many tacos as they could ever want. Tacos, it goes without saying, were his favorite food.
Noah had the makings of a great man, his uncle, Alexis Haller, said.
“He would have been a backbone of our family for years to come,” he said. “His loss, and our loss, are deep indeed.”
During the service, Noah’s twin sister, Arielle, and an older sister sat on their parents’ laps.
After paying his respects to the family, Fairfield police Lieutenant James Perez said the sight of the child-size casket, which lay closed and surrounded by flowers, was heartbreaking.
“I’ve been to a lot of funerals, but not one where the casket was that small,” Perez said, shaking his head side to side. “It literally rendered me speechless.”
The parents’ grief, he said, was painful to witness.
“They’re just devastated,” he said. “I think they’re just in a fog. They’re not really — they’re just here.”
Governor Dannel Malloy had been scheduled to meet with Noah’s family in Fairfield for a few minutes before continuing on to Newtown for the funeral of Jack Pinto. But when he arrived, he had no choice but to stay, Perez said.
“The atmosphere is so devastating that I think he couldn’t leave,” Perez said. “He just couldn’t leave.”
Before the service began, authorities redoubled security in response to a phone threat made against a Newtown church on Sunday that caused a Mass to be halted in the middle of the homily.
On Monday morning, police swept the Fairfield funeral home with bomb detection dogs, and posted dozens of officers and state troopers outside.
“This is a time for the families to grieve, and we wanted to ensure that nothing, no deviant individuals, were going to do something that would require us to interrupt them,” said Chief Gary MacNamara of the Fairfield Police Department.
“No one should take away the opportunity for this family to grieve,” he continued. “We weren’t going to allow that to happen.”
In Newtown, Jack Pinto was laid to rest wearing a New York Giants football jersey with the number of his favorite player, receiver Victor Cruz. Jack was one of the youngest members of a youth wrestling organization, and dozens of boys attended in gray wrestling T-shirts.
Luke Wellman, 10, remembered a boy who loved football and worshiped Cruz, who played in Sunday’s game with “Jack Pinto ‘My Hero’ ” written on one of his cleats.
“I’m here to support my teammate and friend,” he said.
A mourner, Gwendolyn Glover, said the service carried a message of comfort and protection, particularly for other children. “The message was: You’re secure now. The worst is over,” she said.
During the service, a family friend, Mary Radatovich, said that from birth, Jack “commanded all the attention in a room. Who could ignore that beautiful energy, the sparkle in his eye, or that spirit that clearly said, ‘I am here and I am something special’? ”
“We cannot but feel the pain of losing him, but we will never forget the joy of loving him.”
A friend, Nolan Krieger, 8, left the funeral home rubbing his eyes. “I used to do everything with him,” Nolan said. “We liked to wrestle. We played Wii. We just played all the time. I can’t believe I’m never going to see him again.”
The same funeral home will conduct services for at least nine more victims in coming days.
Material from Globe wire services was included in this report. Bill Greene and John R. Ellement of the Globe staff contributed to this report.