In one of the worst school shootings in American history, an 18-year-old gunman in body armour massacred at least 21 people, including 19 children and two adults at an elementary school in Texas state, with an emotional President Joe Biden urging lawmakers to “turn this pain into action” to control the powerful gun lobby.

The youth opened fire at Robb Elementary School in Uvalde town, Texas, 134 km from San Antonio, at about 11.30 AM on Tuesday before he was killed by law enforcement, officials said.

Investigators say the suspect was armed with a handgun, an AR-15 semi-automatic rifle and high-capacity magazines.

Texas Governor Greg Abbott identified the killer as Salvador Ramos, a resident of the area where the school was located. The shooter’s motive remains unclear.

The teenager is suspected of shooting his grandmother at the start of the rampage, US media reports said.

“He shot and killed horrifically, incomprehensibly. Fourteen students and a teacher were killed,” Abbott said. Later the toll was raised to 19 children and two adults dead.

Two law enforcement officers were shot but are expected to recover, Abbott said.

Names of the deceased and other details were yet to be released. According to the school website, its students are aged between 5 years and 11 years.

Chief of Police, Uvalde, Pete Arredondo said the “mass casualty event occurred at Robb Elementary School at about 11:32 this morning”. He said the killer acted as a lone wolf – who was shot dead in a police exchange.

The deceased children are in the second, third and fourth grades – aged between 7 years and 10 years, he said.

US President Joe Biden was briefed on the shooting during his return flight from Japan where he attended the Quad Summit.

In a prime-time address on Tuesday, a visibly emotional Biden asked what it would take to convince fellow lawmakers that it’s time to act.

President Biden again tried to comfort a nation grieving after a mass shooting, urging action to counter powerful gunmakers and repeatedly questioning why the country he leads lacks the backbone to stem the bloodshed.

How many scores of little children who witnessed what happened seen their friends die as if they’re on a battlefield, for god’s sake, said Biden. To lose a child is like having a piece of your soul ripped away. There’s a hollowness in your chest.

Turning to the issue of gun control legislation, Biden implored lawmakers to turn this pain into action” as he ticked through some of the mass shootings since the 2012 massacre at Sandy Hook Elementary School in Newtown, Connecticut, when he was vice president.

“I am sick and tired of it. We have to act. And don’t tell me we can’t have an impact on this carnage,” he said, asking: Why do we keep letting this happen?”

“Where in God’s name is our backbone to have the courage to deal with and stand up to the lobbies? he said.Biden has ordered the US flag to be flown at half-mast until sunset on Saturday, May 28, in memory of those killed in Texas.

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