United States President Barack Obama issued a proclamation ordering that the flag of the US shall be flown at half-staff at the White House and upon all public buildings and ground, at all military posts and overseas diplomatic missions as a mark of respect for the victims of the shooting.
"We are all stunned, shocked, and distraught by this tragic shooting, by this violent act, and by the loss of so many young children. Our hearts go out to the families and friends of the students, teachers, and educators killed and wounded in Newtown, Connecticut," said House Minority Leader, Nancy Pelosi.
"The entire nation will continue to stand as a source of support to this community in the days and weeks to come," Pelosi said.
US Senator Mark Begich said he was deeply saddened by the "deplorable" act of violence against children, who are the most vulnerable of individuals.
House Democratic Whip Steny Hoyer described the incident as a parent's worst nightmare and called it a "senseless tragedy".
"There can be no consolation other than to know that they have the heartfelt prayers and support of an entire nation," Hoyer said.
Photograph: U.S. President Barack Obama wipes a tear as he speaks about the shooting at Sandy Hook Elementary School in Newtown, Connecticut
Credit: Larry Downing/Reuters