The horrific incident happened at Robb Elementary School in Uvalde, about 85 miles west of San Antonio, today.
Texas governor Greg Abbott announced that 14 students and a teacher had been killed.
Mr Abbott said the suspected gunman, an 18-year-old man, also died and was believed to have been killed by responding officers.
Mr Abbott said the gunman had a handgun and possibly a rifle.
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It is the latest school shooting to have happened in America.
26 people were killed in a shooting at the Sandy Hook Elementary in December 2012.
In Texas a permit is not required for for a person 21 and over to carry a handgun either openly or concealed in most places – a law that came into force on September 1, 2021.