(CNN) -- As relatives began to say goodbye, forever, to their slain children, investigators in Connecticut worked Monday to better understand what happened to them, including digging deeper into the gun and computer use of the 20-year-old man who ended their lives.
In recent days, authorities have established that Adam Lanza shot open an entrance into Newtown's Sandy Hook Elementary School. He fired multiple magazines -- each one with 30 bullets -- from a Bushmaster AR-15 rifle to kill six adults and 20 children from two classrooms. Each victim was shot multiple times before Lanza used a handgun to kill himself.
Why? Authorities haven't given a motive. They are looking into bits and pieces of the shooter's home computer, a law enforcement official said Monday.
The hope is that searching the smashed computer -- including e-mails Lanza may have sent and websites he may have visited -- will shed light on his thinking before Friday's shooting, according to the official.
Authorities are also investigating Lanza's history with firearms. The three weapons found near his dead body were the semiautomatic .223-caliber rifle made by Bushmaster and two handguns made by Glock and Sig Sauer. A shotgun was found in Lanza's car, according to Connecticut State Police Lt. J. Paul Vance.
The weapons belonged to his mother, Nancy Lanza, who was found shot dead in her Newtown home on Friday. She was a firearms collector who shot them and went to gun ranges, Bureau of Alcohol, Tobacco, Firearms and Explosives spokeswoman Debora Seifert said Monday.
The two -- the mother and the son who presumably killed her -- even went to a gun range together. From what the ATF has been able to determine thus far, "their most recent visit was more than six months ago," Seifert said.
Beyond these developments, officials overall were tight-lipped Monday about the details of their investigation. Hundreds of state troopers, detectives and other law enforcement personnel on the case were analyzing every round of ammunition from every weapon, probing the gunman's medical history and interviewing witnesses, said Vance, the state police spokesman.
Investigators plan to interview the two adults wounded "in their lower extremities" in the shooting. The hope is that the two -- whom authorities have not identified, though a parent last week said one was a vice principal at the school -- could play a key role in helping to reconstruct what happened "when it's medically appropriate," said Vance.
"I'm not at liberty to discuss any of the information so far uncovered, but suffice it to say ... we will cover every single facet," the police spokesman said of the investigation.
First funerals and addressing 'the unthinkable'
The anguish caused by the shooter was visible Monday outside a Newtown funeral home in the pained faces of young and old who paid their respects to 6-year-old Jack Pinto.
One of the sports fanatic's idols, New York Giants receiver Victor Cruz, paid tribute during his game Sunday by writing "Jack Pinto My Hero" on his cleats. Afterward, the NFL player said he is "amazed" Jack's family chose to bury the boy wearing a child-size Cruz jersey.
"I don't even know how to put it into words," Cruz said.
The 6-year-old himself was a budding athlete. Shortly before his death, he wrestled in his first match and earned a medal, said New Milford Youth Wrestling Association President Ken Linder.
Many of his teammates wore medals into Jack's funeral Monday. Others, many of them about his age, came in Newtown youth sports shirts. The funeral home couldn't contain the mourners, with the line extending to the street.
Jack wasn't the only one remembered Monday. So, too, was Noah Pozner, another 6-year-old whose family said he could get what he wanted just by batting his long eyelashes.
Noah loved playing with his siblings, especially his twin sister. They still don't know how their brother died, Noah's aunt said.
"How do you tell them that's how their brother died?" Victoria Haller asked. "It's the unthinkable, really."
The heartbreaking ritual of sending off Newtown's victims began Monday and will continue for days.
Jessica Rekos on Tuesday. Benjamin Wheeler on Thursday. Madeleine Hsu, Friday. All of them 6 years old.
Once all the funerals end, residents say it's unlikely their tight-knit community will ever be the same.
"It's incomprehensible, the pain here," Darla Henggeler said. "You can't imagine. We're still in shock. I can't let my heart go there because it's so overwhelming.
"Once it settles in, I think my heart will break."
What's next for Sandy Hook's students
It's possible no one will ever know why Adam Lanza killed his mother in their home before taking her guns and massacring little children, none of them older than seven.
Citing school authorities in Newtown, Vance said Monday, "There was no connection between the shooter and the school."
But one mother told CNN Monday that Adam Lanza once attended Sandy Hook Elementary. Cynthia Jaroszewksi said he was in the same first- and third-grade classes with her daughter, Rebecca.
As to Sandy Hook's current students and faculty, they weren't in class Monday and will be out "until further notice," Newtown Police Lt. George Sinko said.
When classes do resume, it will be in a different place, in a different town.
Authorities have said students from Sandy Hook will eventually resume their studies at Chalk Hill Elementary in neighboring Monroe, Connecticut, with Gov. Dannel Malloy saying he's signed an order to expedite such a move.
In fact, moving trucks were parked outside the Newtown school Monday, to transport supplies and equipment to their home.
Other students in the town of 27,000 will be back in class Tuesday, after a 2-hour delay from standard start times.
"Be assured that the safety of your children and our staff are our first priority," Superintendent Janet Robinson told parents in an e-mail. "(Police) Chief (Michael) Kehoe along with his colleagues from the State Police and surrounding communities are implementing a security plan which will provide increased presence at all of our schools."
Massacre stirs debate about gun control
Preventing future Newtowns isn't just a concern in Connecticut. Nationwide, the massacre has spurred talk about gun violence and what can be done to prevent it.
President Barack Obama's call for change was the centerpiece of his address Sunday night before hundreds at Newtown High School. Referencing other mass shootings over the last two years, he said, "These tragedies must end."
Americans can't "honestly say we're doing enough to keep our children -- all of them -- safe from harm," Obama said. To that end, he promised, "In the coming weeks, I will use whatever power this office holds to engage my fellow citizens -- from law enforcement to mental health professionals, to parents and educators -- in an effort aimed at preventing more tragedies like this."
While gun rights groups like the National Rifle Association have been largely silent since Friday's shooting, others have spoken up.
Malloy, Connecticut's governor, said Monday, "I'd love to hear the people argue that we need 30-round magazines and that's somehow tied to the right to bear arms. We're not talking about basic weapons that are used in hunting."
Sen. Joe Manchin, a conservative Democrat from West Virginia and "proud gun owner," said he's now committed to bringing "the dialogue that would a total change" all because of what happened in Newtown.
"Who would have ever thought, in America or anywhere in the world, that children would be slaughtered?" he told CNN. "It's changed me."
The debate was playing out not only in Washington, but all across America.
Participants in a candlelight vigil in New York City passed around a petition calling for greater gun control, Joe Josephs told CNN's iReport.
John Licata told CNN's iReport that there needs to be better vetting before people buy guns and assault weapons should be banned -- something Sen. Dianne Feinstein, D-California, has said she'll propose once the new Congress convenes in January.
CNN iReporter Jameson Riley said the shooting shows the need for more armed guards in schools. Riley, a gun owner, said that the recent mass shootings have made him consider getting a concealed weapon permit.
"I would absolutely carry a concealed weapon. I have a 2-year-old daughter, and she is the light of my life," he said. "And I would like to protect her."
Others said Americans shouldn't change how they live, contending that doing so is a victory for those responsible for mass shootings.
"Yes, I hugged my son so tight when he got home from school that day that he asked what was wrong," one CNN.com commenter wrote. "But I refuse to let evil monsters intimidate me into living my life -- or raising my son -- in fear."
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