Vance said the police received a 911 call at around 9:30 in the morning (local time) about the shooting. The school has been evacuated and the police is extensively searching the "every door and crack of the school" for information about the shooter and the motive.
A woman on the scene told CNN that "20 parents were told that their children are dead. It was aweful."
The police set up a staging area outside the school where all the students were escorted to and reunited with tensed and worried parents.
Vance said the scene has been secure and many agencies are working together to investigate the horrific incident.
"The President is receiving regular updates as more information becomes available about this incident," said White House Press Secretary, Jay Carney, at his daily news conference.
Image: A woman waits to hear about her sister, a teacher, following a shooting at the Sandy Hook Elementary School in Newtown, Conn., about 60 miles (96 kilometers) northeast of New York City, Friday, Dec. 14, 2012. An official with knowledge of Friday's shooting said 27 people were dead, including 18 children. It was the worst school shooting in the country's history. (AP Photo/Jessica Hill)