In this Oct. 28, 2013, aerial file photo, workers use backhoes to remove rubble during the demolition of Sandy Hook Elementary School in Newtown, Conn., where gunman Adam Lanza killed 20 children and six adult educators on Dec. 14, 2012. An open house for the new school, erected on the same site, is set for Friday, July 29, 2016. (AP Photo/Jessica Hill, File)
This Oct. 28, 2013, aerial photo shows the Sandy Hook Elementary School, relocated to the former Chaulk Hill School building in Monroe, Conn., after the original building in neighboring Newtown was razed following a Dec. 14, 2012, shooting rampage where 26 people were killed. A threat Wednesday, Oct. 1, 2014, led to the evacuation of the new Sandy Hook Elementary School in Monroe. The superintendent's office said the students were being moved to a nearby school where they could be picked up by their parents. (AP Photo/Jessica Hill)
Connecticut State line up before a ceremony honoring responders to the Sandy Hook Elementary School shooting in December 2012 at Rentschler Field in East Hartford, Connecticut. (AP Photo/Journal Inquirer, Jared Ramsdell) ** FILE **
FILE - In this Jan. 14, 2014 file photo, a woman waits at a staging ground area where families are being reunited with Berrendo Middle School students after a shooting at the school in Roswell, N.M. Although still relatively rare, there?s been no real reduction in the number of school shootings since security was beefed up around the country with measures such as safety drills and the hiring of police officers, after the rampage at Connecticut's Sandy Hook Elementary School in December 2012. (AP Photo/Roswell Daily Record, Mark Wilson, File)
** FILE ** In this Dec. 15, 2012, file photo, shop owner Tamara Doherty paces outside her store just down the road from Sandy Hook Elementary School in Newtown, Conn. (AP Photo/David Goldman, File)
Family members of two children killed in a shooting rampage at Sandy Hook Elementary School in Connecticut, Mark Barden, left, who lost his son 7-year-old Daniel, and Nicole Hockley, who lost her 6-year-old son Dylan, listen to questions during a newsconference on a bill introduced that would expand gun background checks in New Hampshire. , Tuesday, Jan. 21, 2014 in Concord, N.H. (AP Photo/Jim Cole)