Santa Fe, Texas school shooting: 10 dead, 10 wounded; suspect identified as Dimitrios Pagourtzis

A student is in police custody following a shooting at a Texas high school Friday morning that left 10 people dead and another 10 wounded, making it one of the deadliest school shootings in U.S. history.

Here are the key things to know about the shooting at Santa Fe High School outside Houston:

Here other developments from the day about the deadly shooting:

Dimitrios Pagourtzis, a 17-year-old student at the school, has been arrested and is being held on capital murder charges in connection with the shooting, according to the Galveston County Sheriff's Office.

According to the AP, Pagourtzis is a football player on the school's junior varsity team and is a member of a dance squad with a local Greek Orthodox church.

"I played football with him for three years," Rey Montemayor III, a senior at the school, told the Daily Beast. "He was cool to me. I lifted with him a couple of times."

"I talked to him once or twice," 15-year-old student Mateo Twilley told CNN. "He was really quiet and wore a trench coat almost every day."

The suspect was hiding a shotgun under his trench coat on Friday when he waked into school and opened fire, according to Lt. Gov. Dan Patrick.

On Friday afternoon, Texas. Gov. Greg Abbott offered new details about the investigation into the deadly shooting as part of a press conference that included Sen. Ted Cruz and Lt. Gov. Patrick.

Among the new information Abbott provided:

"This is not acceptable in the state of Texas or in this country. This must end, and we must do everything we can," Lt. Gov. Patrick said. "We can't protect every parking lot and every stadium and every building, but we can sure do better."

Leila Butler, a sophomore at the school, told ABC13 fire alarms at the school went off around 7:45 a.m. local time. She said some students heard shots before sheltering off campus.

"I heard four shots," student Paige Curry told ABC13. "'It was real this time. It wasn't real last time."

In February, the school was placed on lockdown after popping sounds were heard; no threat was identified.

Student Dakota Shrader told reporters she heard the fire alarm, but didn't think anything of it as she exited the classroom. But then she heard three gunshots, and said she was immediately told to run by teachers. Shrader ran with a classmate and found shelter, where she called her mother.

"I shouldn't be going through this. It's my school. This is my daily life. I shouldn't have to feel like that," Shrader said. "I feel scared to even go back."

Senior Logan Roberds told the Associated Press he was near the school's art room when he heard a fire alarm and left the building with other students. Once outside, Roberds said, he heard two loud bangs. He initially thought somebody was loudly hitting a trash can. Then came three more bangs.

"That's when the teachers told us to run," Roberds said, who said he suddenly realized, "Oh my God, this is not fake. This is actually happening."

Sante Fe is about 30 miles outside Houston.

This shooting comes just more than three months after 17 people, including 14 students, were killed following a shooting at Marjory Stoneman Douglas High School in Parkland, Fla.. Since that shooting, several of the students have become high-profile activists, calling on elected officials to enact tougher gun-control legislation.

On Thursday morning, at a conference in Los Angeles for education writers, shooting survivor and gun-control advocate David Hogg offered a chilling prediction in light of Friday's deadly shooting.

"There is someone alive right now that will not be alive at this time tomorrow and has never even thought about gun violence, but everyone around them will have to for the rest of their lives," Hogg said, according to Houston Chronicle education reporter Lindsay Ellis, who was in attendance.

Hogg weighed in on Twitter Friday morning after seeing reports of the shooting in Texas, blasting politicians for "acting" like they cared "when in reality they just want to boost their approval ratings before midterms."

Delaney Tarr, one of Hogg's classmates, also weighed in on Twitter.

On April 20, students from Santa Fe High School participated in a walk-out to protest gun violence as part of the national #NeverAgain movement led by the teenage Florida shooting survivors.

When news of the shooting first broke, President Trump noted on Twitter, "Early reports not looking good."

Later Friday morning, during an event in the East Room at the White House, the president offered support to those affected by the attack.

"This has been going on to long in our country. Too many years, too many decades now," Trump said. "My administration is determined to do everything in our power to protect our students, secure our schools and to keep weapons out of the hands of those who pose a threat to themselves and to others."

Several local politicians posted on social media about the shooting, some offering condolences and others calling for gun-law reform.

This is a breaking news report. Check back for updates.