Last Updated 10:29 a.m. ET
NEWTOWN, Conn. The massacre of 26 children and adults at a Connecticut elementary school elicited horror and soul-searching around the world even as it raised more basic questions about why the gunman, a 20-year-old described as brilliant but remote, would have been driven to such a crime and how he chose his victims.
CBS News has learned that all of the dead have been identified by authorities with the help of pictures provided by grieving parents and family members.
Connecticut State Police spokesman Lt. Paul Vance told "CBS This Morning: Saturday" that the bodies have been removed from the school, which remains a crime scene.
Investigators were trying to learn more about the gunman, Adam Lanza, and questioned his older brother, who is not believed to have been involved in the rampage at Sandy Hook Elementary. Police shed no light on the motive for the nation's second-deadliest school shooting.
At a Saturday morning press briefing Lt. Vance said that investigators at the school crime scene and at the secondary crime scene - the home of the shooter's mother - did produce "very good evidence."
"We're hopeful it will paint a complete picture as to how and why this unfortunate incident occurred," he said.
Lt. Vance also confirmed that the gunman was not allowed into the elementary school and had forcibly entered the building.
He also said there have been other arrests associated with this investigation.
In tight-knit Newtown on Friday night, hundreds of people packed St. Rose of Lima church and stood outside in a vigil for the 28 dead 20 children and six adults at the school, the gunman's mother at home, and the gunman himself, who committed suicide. People held hands, lit candles and sang "Silent Night."
"These 20 children were just beautiful, beautiful children," Monsignor Robert Weiss said. "These 20 children lit up this community better than all these Christmas lights we have. ... There are a lot brighter stars up there tonight because of these kids."
One parent whose children had escaped the event felt a different emotion: "I feel in some respect guilty because I have my baby here, and I just hope anybody who needs help . . . I feel terrible."
Lanza is believed to have suffered from a personality disorder and lived with his mother, said a law enforcement official who was briefed on the investigation.
Lanza shot his mother, Nancy Lanza, drove to the school in her car with at least three guns, including a high-powered rifle that he apparently left in the back of the vehicle, and shot up two classrooms around 9:30 a.m. Friday, law enforcement officials said, speaking on condition of anonymity.
A custodian ran through the halls, warning of a gunman, and someone switched on the intercom, perhaps saving many lives by letting them hear the chaos in the school office, a teacher said. Teachers locked their doors and ordered children to huddle in a corner or hide in closets as shots echoed through the building.
The well-liked principal, Dawn Hochsprung, was believed to be among the dead. A woman who worked at the school was wounded. An update on victims' identities was possible Saturday morning, state police Lt. Paul Vance said Friday evening.
A law enforcement official speaking on condition of anonymity said investigators believe Lanza attended the school several years ago but appeared to have no recent connection to it.
At least one parent said Lanza's mother was a substitute teacher there. But her name did not appear on a staff list. And the official said investigators were unable to establish any connection so far between her and the school.
Lanza's older brother, 24-year-old Ryan Lanza, of Hoboken, N.J., was questioned, but a law enforcement official said he was not believed to have had a role in the rampage. Investigators were searching his computers and phone records, but he told law enforcement he had not been in touch with his brother since about 2010.
The officials spoke on the condition of anonymity because they were not authorized to discuss the unfolding investigation.
At one point, a law enforcement official mistakenly identified the gunman as Ryan Lanza. Brett Wilshe, a friend of Ryan Lanza's, said Lanza told him the gunman may have had his identification. Ryan Lanza apparently posted Facebook page updates Friday afternoon that read, "It wasn't me" and "I was at work."
For about two hours late Friday and early Saturday, clergy members and emergency vehicles moved steadily to and from the school. The state medical examiner's office said bodies of the victims would be taken there eventually for autopsies.
A law enforcement source told CBS News that Adam Lanza had three weapons with him during the attack: Two handguns (a Sig Sauer and a Glock), and a Bushmaster .223 assault rifle; spent shells were found in the school. Those three weapons were registered to his mother.
There was also a fourth weapon (a long gun) found in the car he drove to the school.
In addition, the source told CBS News there were "a few" other weapons found at the mother's house. The registry of the weapon in the car and at the house are still be checked. The tracing of all the weapons - such as where and when they were purchased - is still being conducted.
The Associated Press reports a Henry repeating rifle, an Enfield rifle and a shotgun were recovered. It was not clear exactly where those weapons were found.
Adam Lanza and his mother lived in a well-to-do part of prosperous Newtown, about 60 miles northeast of New York City, where neighbors are doctors or hold white-collar positions at companies such as General Electric, Pepsi and IBM.
Lanza's parents filed for divorce in 2008, according to court records. His father, Peter Lanza, lives in Stamford, Conn., and works as a tax director for General Electric.
The gunman's aunt Marsha Lanza, of Crystal Lake, Ill., said her nephew was raised by kind, nurturing parents who would not have hesitated to seek mental help for him if he needed it.
"Nancy wasn't one to deny reality," Marsha Lanza said, adding her husband had seen Adam as recently as June and recalled nothing out of the ordinary.