CONNECTICUT police confirm that at least 27 people - including 18 children have been killed
President Obama has since given a tearful press conference, hinting that he may be in favour of stricter gun laws in light of the killings, saying: "As a country we have been through this too many times.
"We are going to have to come together and take meaningful action to prevent tragedies like this, regardless of the politics."
He has also ordered the White House flag to fly at half mast out of respect to the victims.
A SHOOTING at a US elementary school has reportedly killed dozens of victims including children
Fear ... children comfort each other outside Sandy Hook Elementary School
One mother told CBS that the school was like a “war zone”.Her child said he had bullets “whizzing by” him in the hallway and that a teacher pulled him into a classroom.
Harrowing ... a woman waits to hear about her sister who works as a teacher at the school
Earlier US reports speculated that the shooter was the father of a pupil at the school, aged 20 from New Jersey.
A Republican congressman John Frey, who has relatives at the school, also said the madman was masked.
Shocking ... shooting at Sandy Hook Elementary School
Parent Stephen Delgiadice said his eight-year-old daughter heard two big bangs and teachers told her to get in a corner.Teams of officers are on the scene, some with dogs, as a thorough investigation continues.The town is located in Fairfield county, one of the wealthiest in the US.
Escape ... a mother runs with her children as police stand guard
One parent, Brenda Lebinski, whose daughter is in the third grade, described how children emerged from the school building covered in blood.
She said: “It was horrendous, everyone was in hysterics - parents, students.
"There were kids coming out of the school bloodied. I don’t know if they were shot, but they were bloodied.”
Distraught ... woman comforts child at Sandy Hook Elementary School
In a statement, British Prime Minister David Cameron expressed his condoleces, saying: "My thoughts are with those who have been devastated by the Connecticut shootings.
"The death of so many children is truly heartbreaking."
Security ... armed cops arrive at the school
White House spokesman Jay Carney said it was too early to enter an immediate debate about whether Obama would back more stringent gun control legislation.
“I don’t think today is that day," he said. "I think it’s important on a day like today to view this, as I know the president as a father does, and I as a father and others who are parents certainly do, which is to feel enormous sympathy for families that are affected."
Pain ... a woman holds a child as people line up to enter the Newtown Methodist Church
Obama was told of the shooting at 10.30am by his top anti-terror and homeland security advisor John Brennan in the Oval Office, Carney added.
Connecticut State Police Lieutenant Paul Vance told a press conference: “The shooter is deceased inside the building. The scene is secure.”
Declining to confirm the number of dead, he added: “There were several fatalities at the scene, both students and staff."
Comfort ... a woman speaks with a Connecticut State Trooper
A local NBC news channel said a hospital in nearby Danbury had reported receiving several wounded.
Sandy Hook Elementary School teaches children from kindergarten through fourth grade - roughly ages 5 to 10.
This shooting rivals the massacres at Virginia Tech in 2007 where 32 people were killed and at Columbine High School in 1999 where 13 were gunned down.
Lock down ... aerial shot of Sandy Hook Elementary School
The worst mass school murder in American history took place on May 18, 1927, in Michigan, when a former school board member set off three bombs that killed 45 people.
Today’s tragedy has chilling echoes of the 1996 Dunblane school massacre in Scotland when killer Thomas Hamilton went on the rampage shooting dead 16 children