Federal law enforcement officials said the death toll was expected to rise. They spoke on condition of anonymity because they were not authorised to release investigative details.
At least 19 children are dead after an 18-year-old gunman opened fire at a Texas elementary school, officials said.
The death toll also includes two teachers, while the teenage gunman was also shot dead by police.
It was the deadliest shooting at a US grade school since a gunman killed 20 children and six adults at Sandy Hook Elementary in Newtown, Connecticut, almost a decade ago.
And it came just 10 days after a gunman in body armour killed 10 black shoppers and workers at a supermarket in Buffalo, New York, in what authorities say was a racist attack.
Federal law enforcement officials said the death toll was expected to rise. They spoke on condition of anonymity because they were not authorised to release investigative details.
The gunman entered Robb Elementary School in Uvalde with a handgun and possibly a rifle, Governor Greg Abbott said.
Officials did not immediately reveal a motive, but the governor identified the assailant as Salvador Ramos and said he was a resident of the heavily Latino community about 85 miles (135 kilometres) west of San Antonio.
