President Obama has spoken of his "overwhelming grief" over the worst school shooting in US history.

It is reported that the gunman, who killed 27 people, may have suffered from a personality disorder.

Adam Lanza was a former pupil at Sandy Hook Elementary school in Connecticut and killed himself after the shootings.

Maryanne Jacobs - the school's assistant librarian - hid with 18 children as the killer went on the rampage: