San Antonio-based South Texas Blood and Tissue announced May 24 it had sent 25 units of blood to a hospital in Uvalde, Texas, helping to boost emergency aid to victims of a local school shooting that has claimed more than 20 lives, including 18 students.

Law enforcement officials confirmed a death toll of 18 children and three teachers in a shooting at Robb Elementary School.

Gov. Greg Abbott announced the now-deceased shooter as an 18-year-old, but officials said the investigation was ongoing into how the shooter came to possess the weapons he carried to Robb Elementary as well as a motive.

“Texans across the state are grieving for the victims of this senseless crime and for the community of Uvalde,” Abbott said in a statement.

South Texas Blood and Tissue issued a statement that, thanks to blood donors, it was able to initially send 15 units of blood to Uvalde Memorial Hospital shortly after news of the school shooting broke.

“Later this afternoon, we received a request and sent an additional 10 units of blood to a hospital in Uvalde,” the STBT statement said.

STBT officials said they were continuing to work with area hospitals to make blood available as it is needed “and to rebuild their supply for other patients in need.”

“This tragedy highlights the importance of always having blood available on the shelf and before it’s needed,” the statement said.

STBT urged community members to consider donating blood; individuals may do so by visiting www.southtexasblood.org or calling 210-731-5590.

San Antonio’s University Hospital announced it had received two shooting patients: a 66-year-old woman and a 10-year-old girl.

“Our hearts are breaking for the people impacted by this senseless tragedy. Our thoughts are with the patients, families, students, teachers and the people of this community,” a University Hospital statement said.

Bexar County Judge Nelson Wolff said the county sent personnel and materials from its office of emergency management, the medical examiner’s office and the sheriff’s office to support ongoing operations in Uvalde.

"It is with profound grief and broken hearts that we learn about the news coming our way this afternoon. We stand united with the community in Uvalde and offer our assistance. We also mourn with them over the lives of those children and adults lost to violence,” Wolff said.

President Joe Biden briefly addressed the nation before 8 p.m. May 24, offering prayers to those immediately affected by the Uvalde shooting and urging legislative action to shore up gun control.

“We have to act, and don’t tell me we can’t have an impact on this carnage," Biden said.