U.S. President Barack Obama and other Americans paused Friday morning, remembering the children and adults gunned down by a 20-year-old in Newtown, Connecticut, one week ago.

Church bells rang in Newtown and other U.S. towns and cities for the victims, while mourners stood in silence. Authorities say Adam Lanza killed his mother, then went to an elementary school, murdering 20 children and six adults before killing himself.

The attack at Sandy Hook Elementary was the second-worst school shooting in U.S. history.

The mass shooting has renewed U.S. debate on gun control and gun violence. On Thursday, a U.S. federal gun violence task force, formed in response to the shootings, met for the first time.

Vice President Joe Biden told the group the Obama administration was determined to find solutions that include input from the mental health and education communities as well as from legal experts addressing the constitutional right of U.S. citizens to own weapons.

President Obama earlier this week called on Congress to reinstate an assault weapons ban that lapsed in 2004. The gunman in the Newtown attack used a military-style weapon.

The powerful National Rifle Association — the largest gun rights organization in the U.S. — is holding a news conference Friday in Washington. The group this week said its members were “shocked” by the Connecticut shootings but wanted to give the families of the victims more time to mourn before making additional statements.

Funerals resume on Friday for the victims, with families going through the painful process of saying final farewells to their loved ones.

The worst U.S. school shooting occurred in 2007, when a gunman opened fire at a Virginia university, killing 32 people before killing himself.