A gunman killed at least 19 children and two adults at Robb Elementary School in Uvalde, Texas, about 90 miles west of San Antonio, on Tuesday.

Texas Governor Greg Abbott said May 24 the shooter, a local 18-year-old, has died, believed to have been killed by responding law enforcement. He identified the attacker as Salvador Ramos, saying he was armed with a handgun, and possibly a rifle.

The governor added, “It is believed that two responding offers were struck by rounds, but have no serious injuries.”

Some students and staff are being treated in nearby hospitals.

The incident is believed to be the worst school shooting since the 2012 attack at Sandy Hook Elementary in Newtown, Connecticut, in which in the attacker killed 26.

Archbishop Gustavo Garcia-Siller of San Antonio tweeted, "God have mercy on our children, their families, their communities. Darkness is dense with one more shooting in our country. Let us help one another to spark light and warmth. May we keep each other in company. Prayers are needed."

And Bishop Michael Olson of Fort Worth has tweeted, "Let us pray for the families of these children killed or traumatized by this evil action and let us take serious steps forward in protecting vulnerable life and promoting justices for the safety of our children."

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This story was updated at 11:25 p.m. MDT.