UPDATE (4:20 p.m. ET): The shooter used his father's guns, a shotgun and .38 revolver, to carry out his attack, Fox News reports. They had been legally purchased.
UPDATE (3:05 p.m. ET): Texas Gov. Greg Abbott addressed reporters from Santa Fe. This is “one of the most heinous attacks we’ve ever seen in Texas,” he said.
"We grieve for the victims and we pray for the families who are suffering and will continue to suffer in the days to come," he said. “Nothing can prepare a parent for the loss of a child.”
Abbott said he is preparing to meet with the state legislature, parents and students for roundtable discussions "on swift solutions to prevent tragedies like this."
Abbott confirmed that 10 were killed and 10 others injured in Friday's shooting.
"Hold your children close tonight and let them know how much you love them."
Abbott added that there were very few warning signs leading up to today's shooting. Although the shooter had a few alarming Facebook posts, he had an otherwise "pretty clean" slate.
UPDATE (2:18 p.m. ET): The shooter has been identified as 17-year-old Dimitrios Pagourtzis. When he entered the school, he was wearing a trench coat and was armed with a shotgun, an assault-style rifle, and a pistol, according to reports.
Students told local media that the suspect had often worn the same unusual outfit to school.
Dustin Severin, a 17-year-old student, told local NBC affiliate KPRC that he saw Pagourtzis in the hallway shortly before the bullets started flying — and that he was wearing his usual outfit.
"He wears a trench coat every day, and it's like 90 degrees out here," Severin said.
Pagourtzis, Severin added, was the victim of bullying — and not just by other students.
"He's been picked on by coaches before, for smelling bad and stuff like that," Severin said. "And he doesn't really talk to very many people either. He keeps to himself." (NBC News)
UPDATE (12:22 p.m. ET): Possible explosive devices were found at the high school and at an off campus location.
#UPDATE Possible explosive devices have been located at the school and off campus. Law enforcement is in the process of rendering them safe. School has been evacuated. Call 911 if you see any suspicious item. #HouNews #SantaFeISD— Santa Fe ISD (@SantaFeISD) May 18, 2018
UPDATE (11:48 a.m. ET): Harris County Sheriff Ed Gonzalez tells reporters 8 to 10 individuals have been killed, including nine students and one teacher. The gunman, he said, is believed to be a student at the school. Another "person of interest" has been detained.
JUST IN: Sheriff updates on latest on deadly Texas shooting: https://t.co/ja4ueWLNFB— ABC News (@ABC) May 18, 2018
-Between 8-10 fatalities.
-One ISD police officer injured.
-One suspect in custody.
-"Second possible person of interest" detained and being questioned.
-Search of school ongoing. pic.twitter.com/AaZgqBYZeR
UPDATE (11:15 a.m. ET): Local media KRIV is reporting that eight people are dead. An officer has also been shot.
President Trump has tweeted on the horrifying situation.
School shooting in Texas. Early reports not looking good. God bless all!— Donald J. Trump (@realDonaldTrump) May 18, 2018
"We're closely monitoring the situation," Trump said at a summit on prison reform at the White House Friday. "We grieve for the terrible loss of life."
Everyone at every level of government "must work together" to protect our children, he added.
UPDATE: At assistant principal at Santa Fe High School said a suspect is in custody. Injuries have been reported.
UPDATE: A suspect is in custody after reports of an active shooter at a high school south of Houston, an assistant principal at Santa Fe High School says https://t.co/oqRZUFvJK4 pic.twitter.com/U5yR7Fwr6n— CBS News (@CBSNews) May 18, 2018
The school posted a statement confirming that the situation has been contained.
UPDATE — Santa Fe ISD confirms there were injuries and says the active shooter situation has been “contained pic.twitter.com/x2iZ2W9alP— Shannon Murray (@ShannonMFox4) May 18, 2018
We're hearing reports of an active shooter at a Santa Fe high school in southeastern Texas.
New: Santa Fe TX Independent School District has acknowledged an active shooter incident at Santa Fe High School Friday morning— Jim Sciutto (@jimsciutto) May 18, 2018
The school is currently on lockdown. The police and the Bureau of Alcohol, Tobacco, Firearms and Explosives are responding to the incident.
Santa Fe High School on lockdown after a situation with an active shooter on campus. Witnesses say the shooting took place in an art class on campus between 7:30 and 7:45 a.m.— ABC13 Houston (@abc13houston) May 18, 2018
LIVE COVERAGE: https://t.co/lUUGfKCRsj pic.twitter.com/v28UIsMffX