27 people, 18 of whom were young school children, were shot and killed at a US Elementary school in Connecticut, in what is one of the worst gun massacres in the country's history.

The gunman is believed to be a 20-year-old man with ties to the school. A witness said that two guns were used in the shooting, one of which was a .223-calibre rifle.

The White House said President Barack Obama had been notified about the tragedy and that he had "enormous sympathy for families that are affected."