Barack Obama, the US president, is attended an evening vigil in Newtown, Connecticut, to mourn the dead and console the survivors of a rampage that killed 26 people, including 20 children.
His visit on Sunday to the western Connecticut community comes two days after a man opened fire inside Sandy Hook Elementary School killing 20 boys and girls just six or seven years old.
A Roman Catholic church in Newtown was evacuated on Sunday after a bomb threat was reported by officials during services at the church, which is roughly 1.6km from the site of shooting.
State troopers, police and ambulances were on the scene at St. Rose of Lima Catholic church, according to a Reuters news agency eyewitness.
Obama will visit privately with families of the victims and with emergency personnel who responded to the shootings. He will then speak at an interfaith vigil at Newtown High School.
Speaking tearfully at the White House on Friday, Obama expressed his sympathy as a parent and a president.
He reiterated his message on Saturday morning in his usual weekend radio address, declaring that "every parent in America has a heart heavy with hurt" and asserting that it was time to "take meaningful action to prevent more tragedies like this".
For the president, this is the fourth trip of his presidency to a community still grieving from a mass shooting.
Just last summer, Obama went to Aurora, Colorado, to visit victims and families after a shooting spree at a movie theatre in the Denver suburb left 12 dead.
The Newtown shootings and Obama's vague but declarative call for "meaningful action" has reignited a debate over gun laws and raised an expectation among gun control advocates that Obama will seek changes.
But public opinion in favour of gun control has declined over the years.
Authorities identified the shooter in rampage as Adam Lanza, a 20-year-old, who police say first killed his mother before driving to the school, opening fire in two classrooms and then taking his own life.
While the White House has said that Obama stands by his desire to reinstate a ban on military-style assault weapons, he has not pushed Congress to act.
Some Democratic politicians have called for sweeping new gun-control measures, a move certain to encounter forceful opposition from the nation's pro-gun lobby.
|The killing has revived America's continuing
debate over gun control
On Sunday, Dannel Malloy, governor of Connecticut, became the latest public figure to call for new gun control measures following Friday's rampage.
"These are assault weapons. You don't hunt deer with these things," Malloy said on the CNN program "State of the Union".
He said a lot of guns used in crimes in his state were actually purchased in other states and brought to Connecticut.
"Connecticut has a pretty aggressive law. Probably of the 50 states, I think we're ranked fourth most aggressive in trying to limit access to these kinds of weapons," the governor said.
The mayor of Connecticut's capital city, whose own father was killed with a gun, has urged Washington to take the lead in curbing "an incredible appetite" among Americans for guns.
Pedro Segarra said Connecticut citizens are "very supportive of demilitarising our community and getting these weapons off the streets”.
But the mayor added: "A lot of this really requires action by our central government in Washington."
US politicians have not approved a major new gun law since 1994, and they let a ban on certain semi-automatic rifles known as assault weapons expire in 2004.