Newtown school shooting

In this photo provided by the Newtown Bee, Connecticut State Police lead children from the Sandy Hook Elementary School, following Friday's shooting. Twenty-seven people were killed, including 18 children. It is the worst school shooting in the country's history. (AP Photo/Newtown Bee, Shannon Hicks)

This satellite image provided by Google shows the Sandy Hook Elementary School. A shooting at the school Friday left the gunman dead and at least one teacher wounded. (AP Photo/Google)

Parents leave a staging area after being reunited with their children following the shooting at the Sandy Hook Elementary School, Friday. (AP Photo/Jessica Hill)

Parents leave a staging area after being reunited with their children following the shooting at the Sandy Hook Elementary School, Friday. (AP Photo/Jessica Hill)

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

State Police gather the scene following the shooting Friday. (AP Photo/Jessica Hill)

A mother runs with her children as police above canvass homes in the area following the shooting. (AP Photo/Jessica Hill)

Gov. Dannel P. Malloy, right, talks with officials at a staging area in Newtown. (AP Photo/Jessica Hill)

Law enforcement canvass the area in the aftermath of Friday's shooting. (AP Photo/Jessica Hill)

A man and woman leave the staging area for family around near the scene of a shooting at the Sandy Hook Elementary School. (AP Photo/Jessica Hill)

People embrace at a firehouse staging area for family around near the scene of a shooting at the Sandy Hook Elementary School. (AP Photo/Jessica Hill)

Ambulances leave an area near the scene of a shooting at the Sandy Hook Elementary School, Friday. (AP Photo/Jessica Hill)