Panicked parents looking for their children raced to Sandy Hook Elementary in Newtown, a prosperous New England community of about 27,000 people 60 miles northeast of New York City.
Lanza's older brother, 24-year-old Ryan, of Hoboken, New Jersey, was being questioned, but a law enforcement official said he was not believed to have had a role in the rampage.
US school shooting: All victims have been identified, say police
Newtown: In one of the deadliest mass shootings, a young gunman killed his mother and 26 other people, including 20 children, when he went on a shooting rampage inside a US school, before turning the gun on himself, in one of the deadliest such incidents witnessed in the country.
The shooting at Sandy Hook Elementary School appeared to be the US’ second-deadliest school shooting, exceeded only by the Virginia Tech massacre in 2007, in which 32 people, including two Indians, were killed and 17 others wounded.
The gunman, identified as Adam Lanza, killed his mother at their home and then opened fire inside the school. The 20-year-old killer, carrying at least two handguns, committed suicide at the school, bringing the death toll to 28, authorities said.
“All the victims of school shooting have been identified”, Connecticut police said during a news conference.
As per BBC report, gunman, Adam Lanza ‘forced’ his way inside the school.
Lieutenant Paul Vance told the news conference that the suspect was not voluntarily let into Sandy Hook Elementary School in Newton.
Barack Obama, while addressing the tragedy for the second time since the shooting incident, on Saturday said, "Our hearts are broken today…We grieve for the families of those we lost. And we keep in our prayers the parents of those who survived”. He reiterated his appeal that, "regardless of the politics”, it was time for the country to join together and "take meaningful action to prevent more tragedies like this”.
"The majority of those who died were children — beautiful little kids between the ages of 5 and 10 years old," Obama said at a White House news briefing.
“All the victims of school shooting have been identified”, Connecticut police said during the news conference.
Connecticut State Police spokesman Lt. J. Paul Vance told a press conference in Newtown Saturday that the gunman forcibly entered the school whose doors were locked. He also said investigators had found "very good evidence" and hoped it would answer questions about the gunman's motives but he did not elaborate.
Investigators are looking for answers as to why a 20-year-old gunman shot dead 20 children and six adults in before apparently killing himself were combing the crime scene.
The bodies of those killed at Sandy Hook Elementary School in Newtown, 60 miles north of New York City, were transported to the office of the state medical examiner for post-mortem examinations, state police said.
The father and older brother of the masked gunman, Adam Lanza, are in absolute ‘shock’, according to a report.
Meanwhile, authorities in Hoboken, New Jersey, are questioning Ryan Lanza, the suspected gunman's older brother and Peter, Lanza's father, who lives in Connecticut, CNN reported citing law enforcement sources.
UN Secretary-General Ban Ki-moon voiced his "deepest condolences" over the victims of the school shooting. In a letter to Connecticut Governor Dan Malloy, Ban called the Sandy Hook Elementary School rampage "shocking murders", spokesman Martin Nesirky told reporters.
A relative of the masked gunman has said that the 20-yr-old was ‘obviously not well’. According to a report, family friends in Newtown also described the young man as troubled and described Nancy as very rigid.
Ryan Lanza apparently posted Facebook page updates on Friday afternoon that read, "It wasn't me" and "I was at work”."
Nancy and her husband Peter, Adam's father, divorced in 2009. When they first filed for divorce in 2008, a judge had ordered that they participate in a "parenting education program”, a report said.
At least one parent said Adam Lanza's mother was a substitute teacher there. But her name did not appear on a staff list.
The 20-year-old US school shooting suspect reportedly used heavy-duty firearms that were allegedly registered on his mother’s name.
The New York Times have quoted Adam Lanza’s high school classmates as saying that the school shooting suspect was a quiet and introverted teenager, who was too camera shy for a yearbook photo. Several said he had Asperger syndrome.
CBS News says it appears that Connecticut school shooting suspect planned attack in advance. He shot out glass of school and gained access.
Pope Benedict XVI has written a message to Newtown shooting victims: “I convey my heartfelt grief”.
Flags were ordered to fly at half-staff nationwide in tribute to the victims.
"Evil visited this community today," Connecticut Governor Dan Malloy said of massacre.
Police shed no light on the motive for the attack. The gunman, Adam Lanza, was believed to suffer from a personality disorder and lived with his mother, said a law enforcement official who was briefed on the investigation but was not authorised to discuss it.
On Friday night, hundreds of people packed a Newtown church and stood outside in a vigil for the victims.
"Our hearts are broken today," a tearful President Barack Obama, struggling to maintain his composure, said at the White House. He called for "meaningful action" to prevent such shootings, saying, "As a country, we have been through this too many times."
At least three guns were found — a Glock and a Sig Sauer, both pistols, inside the school, and a .223-caliber rifle in the back of a car, authorities said.
State police Lt Paul Vance said 28 people in all were killed, including the gunman. The school's principal was believed to be among the dead.
Schoolchildren — some crying, others looking frightened — were escorted by police through a parking lot in a line, hands on each other's shoulders.
Authorities gave no details on exactly how the attack unfolded, but police radio traffic indicated the shooting lasted only a few minutes.
Law enforcement officials speaking on condition of anonymity said that Adam Lanza killed his mother, Nancy Lanza, then 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 am.