Nineteen children and two teachers have been killed after a gunman opened fire at a primary school in Texas, the state governor, Greg Abbot said.
The attack happened at Robb Elementary School in the city of Uvalde, around 80 miles west of San Antonio.
Governor Greg Abbott identified the gunman as Salvador Ramos, an 18-year-old from the city who went into the school with a handgun and possibly a rifle.
He is believed to have been killed by police officers and allegedly shot his grandmother before entering the school, Mr Abbott added.
“He shot and killed horrifically, incomprehensibly, 19 students and killed 2 teachers,” he told a news briefing.
He added that two police officers were hit while exchanging gunfire with the suspect and sustained “non-life-threatening injuries”.
A 10-year-old girl and a 66-year-old woman are in critical condition, University Hospital in San Antonio said on Twitter.
President Joe Biden has been briefed on the shooting and will speak later on Tuesday, Karine Jean-Pierre, the White House press secretary, said.
In a statement, the President ordered US flags be flown at half-staff at the White House and other public buildings “as a mark of respect for the victims” until sunset on 28 May.
The school, in a mostly residential neighbourhood of modest homes, has just under 600 students aged from five to 11.
All schools in the local distract were locked down earlier because of gunshots in the area, the Uvalde Consolidated Independent School District said.
Uvalde is home to about 16,000 people.
The shooting came less than two weeks after a gunman opened fire at a supermarket in Buffalo, New York, killing 10 black shoppers and workers in what officials have described as a hate crime.
Dozens of police officers were at the school on Tuesday afternoon, with officers in heavy vests diverting traffic and FBI agents coming and going from the building.
The attack is the deadliest school shooting in Texas history and comes four years after a gunman fatally shot 10 people at Santa Fe High School in the Houston area.