Updated 22:19

This aerial photo shows Sandy Hook Elementary School in Newtown, Conn., right, where authorities say a gunman opened fire inside the school (Julio Cortez/AP).

THE NEWTOWN POLICE Department in Connecticut has confirmed that 27 people have been killed in the school shooting in Newtown, including 20 children, the school principal and the shooter.

Lieutenant Paul Vance said 18 children were pronounced dead at the scene of the shooting at Sandy Hook Elementary School and two later died in hospital. An additional 6 adults were also pronounced dead at the scene and one person was injured.

Vance said the shooter was also pronounced dead at the scene and reports suggest he may have taken his own life. According to AP, a law enforcement official said three guns were found at the scene a Glock and a Sig Saueras and a rifle. The rifle was recovered from the back of a car at the school. The two pistols were recovered from inside the school.

A woman waits to hear about her sister, a teacher, following a shooting at the Sandy Hook Elementary School in Newtown (Jessica Hill/AP).

Vance confirmed there is a secondary crime scene in Newtown and that an adult was found dead at that location. It is understood this individual is the shooter’s mother who was also a teacher at the school but the authorities have not released this person’s name yet. In a second press conference tonight Vance said police would not be releasing the identity of any individuals until their events become clearer.

The lieutenant said the shooting took place in one section of the elementary school in two different rooms.

John Miller of CBS News has reported that one of two brothers is dead and the other is being questioned by police. Earlier, a law enforcement official mistakenly transposed the brothers’ first names and it was thought that the older brother, aged 24-years-old was the shooter.

Connecticut State Police said that the scene was secure and there is a great deal of search warrant activity going on in and out of the state. Lieutenant Vance also confirmed that the authorities in Connecticut are receiving assistance from New Jersey.

Speaking earlier, Governor of Conneticut Dan Molloy said the incident was a “tragedy of unspeakable terms” and said it will “leave a mark on this community and every family impacted by it”.

Earlier Presidnet Barack Obama gave an emotional address from the White House press room in which he said the country’s leaders must “take meaningful action” regardless of politics.

President Barack Obama pauses as he speaks about the elementary school shooting in Newtown (Charles Dharapak/AP).

The shooting is believed to be one of the worst in US history, following the mass April 2007 shootings at Virginia Tech when a gunman left 33 people dead.

Obama said the country has faced “too many of these tragedies” and that he reacted “not as a President, but as anyone else would, as a parent.”

“Nothing can fill the space of a lost child or a loved one,” he said. “They had their whole lives ahead of them”.

Shortly before his statement, Obama ordered that the US flag be flown at half-staff on public grounds.

American flags surrounding the Washington Monument in Washington are lowered to half-staff in a mark of respect for the victims on the Connecticut elementary school shootings (Alex Brandon/AP).

- Additional reporting from Associated Press.