Nineteen children and two adults were killed in a gunfight at Rob Elementary School in Uvalade County on Tuesday, making the slaughter the deadliest school shooting in Texas history.

"My heart is shivered today," said Hal Harrell, an independent school district superintendent at Uvalade, during a tear-jerking press conference Tuesday evening. "We are a small community and we need your prayers to transcend it."

White House officials say President Joe Biden has offered his support to Abbott. Biden instructed all public property and the U.S. embassy to fly flags with half the staff in memory of those killed.

“Tonight, I request the nation to pray for them. Give the parents and siblings the  physically and mentally strong in the darkness they feel right now,” Biden said at a press briefing Tuesday evening.

Earlier on Tuesday, CISD placed all campuses under lockdown in Uvalade after a shootout in the area.

Harrell said the school would be closed for the rest of the school year, although students would be offered mourning counseling.