The shooting unfolded in Santa Fe, a city of about 13,000 people roughly 30 miles (48 kilometers) southeast of Houston.
Houston Texans defensive end JJ Watt has always been known for his connection to the Houston area, and has offered to pay for the funerals of the 10 people killed in the shooting.
The suspect is 17-year old Dimitrios Pagourtzis, law enforcement sources told CBS and NBC News.
Tristen Patterson, a junior at Sante Fe high School, says Pagourtzis didn't show signs of being bullied, but that he rarely talked about himself.
Early Friday morning at Santa Fe High School, a gunman opened fire inside an art class, killing nine students and one teacher. The governor said the assailant meant to kill himself but gave up and told police that he did not have the courage to take his own life. Harris County Sheriff Ed Gonzalez confirmed at a Friday morning news conference that another "person of interest" was detained, and one police officer was injured.
Shana Fisher was killed in the Santa Fe High School shooting on May 18, 2018 in Santa Fe, Texas. An official confirmed explosive devices were found in the school and the "surrounding areas adjacent to the high school", urging nearby residents to keep an eye out for suspicious items.
He says Pagourtzis would sometimes enter the classroom "acting a little bit down or sad". So I don't know.
Pagourtzis is being held in the Galveston County Jail without bond on a capital murder charge.
"There was a girl on the ground", Mr Muehe said, "and he shot her in the head one or two times". Police have not yet said what might have motivated the attack.
The suspect obtained the shotgun and a.38-caliber handgun from his father, who owned them legally, Abbott said.
"He could have killed me right there", he said.
Santa Fe school shooter exchanged 'a lot' of gunfire with police
Several questions remain unanswered following Friday's mass shooting at a Texas high school. Santa Fe police told HuffPost that officers were on the scene.
There are more registered weapons in Texas than in any other state, according to the Bureau of Alcohol, Tobacco, Firearms and Explosives, though some smaller states have more guns per capita.
Santa Fe High School, southeast of Houston, became the scene of the fourth-deadliest mass shooting at a USA public school in modern history, joining a long list of campuses where students and faculty have fallen victim to gunfire. The high school serves about 1,500 students, according to statistics reported to the U.S. Department of Education.
The University of Texas Medical Branch tweeted the update Saturday.
Houston Texans Pro Bowl defensive end JJ Watt plans to pay for the funerals of the 10 victims in the most recent school shooting that took place at Santa Fe High School. The latter two were in "good condition".
This latest shooting is the 101st mass shooting in the USA carried out so far this year. The shooting was the nation's deadliest such attack since the massacre in Florida that gave rise to a campaign by teens for gun control.
Rodriguez said that the week before the shooting, Fisher "stood up to him" by "embarrass (ing) him in class".
"It's been happening everywhere", she said.
The state's Governor Greg Abbott, a Republican, is proud of his pro-gun position.
But Mr Acevedo condemned the "elected officials that ran to the cameras today", saying while they spoke in solidarity and called for prayers, they would "once again do absolutely nothing".