At least 21 people, including 19 children, are dead after an active shooter incident sent a Texas elementary school into lockdown.

Salvador Ramos, abandoned a vehicle before entering the school to "horrifically, incomprehensibly" open fire.

The gunman opened fire at Robb Elementary School - which teaches children aged seven to 10 - in the city of Uvalde before he was killed by law enforcement, officials said.

A fourth-grade teacher, Eve Mireles, was identified as one of the two adult victims.

The attack happened at Robb Elementary School in the city of Uvalde, around 80 miles west of San Antonio.

According to CBS News, the attacker was wearing body armour as he carried out the attack. Another 18-year-old who is suspected of attacking a grocery store in Buffalo, New York, on 14 May was also wearing body armour and carrying a semi-automatic rifle - both of which are commercially available in the US.

The 18-year-old suspect had a handgun, an AR-15 semi-automatic rifle and high-capacity magazines, investigators say.

The teenager is suspected of shooting his grandmother before the rampage.

Local media report he may have been a high school student in the area.

Ramos shot his grandmother before the mass shooting, authorities say, and she remains hospitalized in critical condition.

President Joe Biden called on the US to turn its collective pain into political action following the deadliest elementary school shooting since Sandy Hook in 2012.

French President Emmanuel Macron expressed his condolences over the Texas elementary school shooting, calling it “a cowardly attack.”

Pope Francis expressed his condolences over the Texas school shooting tragedy and sent his prayers to the victims and their families during today’s morning weekly audience. 

German Chancellor Olaf Scholz and Spanish Prime Minister Pedro Sánchez separately expressed their condolences over the Texas school shooting.

School shootings have become recurring emergencies in the US, with 26 recorded last year, according to EdWeek, an education trade publication.