President Joe Biden struck a somber and serious tone, calling for new gun restrictions, in an address to the nation after a shooting at a Texas elementary school.

"When in Gods name are we going to stand up to the gun lobby? When in Gods name do we do what we all know needs to be done?" Biden asked. Biden, who lost both a son and a daughter, was joined by first lady Dr. Jill Biden at the White House on Tuesday night.

"Why are are willing to live with this carnage? Why do we keep letting this happen? Where in Gods name is our backbone?" Biden said adding later, "Its time to act". He directed that American flags be flown at half-staff through sunset Saturday in honor of the victims in Texas.

President Biden called on the nation to pray for the parents and siblings of those dead. "To lose a child is like having a piece of your soul ripped away," he said.

Vice President Kamala Harris said, "our hearts break but our hearts keep getting broken and our broken hearts are nothing compared to the broken hearts of those families. We have to have the courage to take action to ensure something like this never happens again."

White House press secretary Karine Jean-Pierre said that Biden was briefed on the shooting by deputy chief of staff Jen OMalley-Dillon and other members of his senior team aboard Air Force One.

At least 18 children and three adults were killed at Robb Elementary School in Uvalde, Texas, on Tuesday morning. Uvalde is about 85 miles west of San Antonio. The 18-year-old gunman is dead. It's unclear if the number includes the shooter. In addition to 21 dead, three people injured in the shooting remain in serious condition, Gutierrez told The Associated Press.

Hal Harrell, superintendent of the Uvalde Consolidated Independent School District, said that Robb Elementary School will be closed and all school activities will be cancelled until further notice. Harrell also said grief counselors would be available starting Wednesday morning.