Nineteen young children and two adults were killed by gunfire at an elementary school in southern Texas.
The 18-year-old gunman opened fire on Robb Elementary School in the town of Uvalde before being killed by police, officials said.
Investigators say the suspect was armed with a pistol, a semi-automatic AR-15 rifle and high-capacity cartridges.
Salvador Ramos first killed his grandmother, and then had a car accident near the elementary school. He got out of the car with a rifle and entered the school building opening fire on some of the classrooms.
Little is known about Ramos: he was a high school student in the area and shortly before the massacre he contacted a stranger on Instagram telling him that he had a secret he wanted to reveal: "I'm ready to…".
However, he did not tell the girl what was the crazy gesture he had in mind and that he finished a few hours later. On his Instagram account, the killer posted a selfie and photos of the guns, including one with two rifles. It is not known if these are the weapons used for the massacre. What is known is that the boy bought two rifles for his 18th birthday.
Uvalde School Independent District Police Chief Pete Arredondo said the shooting began at 11:32 a.m. local time on Tuesday and that investigators believe the attacker "acted alone during this horrific crime."
Texas Gov. Greg Abbott said the attacker abandoned a vehicle before entering the school to open fire "terribly, incomprehensibly."
One of the adults killed was a teacher, who has been mentioned in the American media as Eva Mireles.