Santa Fe High School Shooting: Alleged Gunman Dimitrios Pagourtzis, 17, in Custody, at Least 10 Dead

A witness described the weapon as a shotgun.

Officials in Texas say a gunman walked into a high school art class and opened fire Friday morning, killing at least 10 people, according to reports.

The shots rang out before 8 a.m. at Santa Fe High School east of Houston, where an assistant principal told KTRK a suspect was quickly taken into custody.

The alleged shooter has been identified as Dimitrios Pagourtzis, a 17-year-old a student. According to reports, a second person, also a student, was also detained.

Nine of the dead are said to be students, along with one fatally shot teacher. 

Officials have also confirmed there were what are believed to be explosives located both at the school and at a site off campus.

Another officer was shot and is listed in critical condition. 

The school was swiftly placed on lockdown as a district statement on Facebook confirmed multiple injuries without initially going into detail.

"This morning an incident occurred at the high school involving an active shooter. The situation is active, but has been contained," the statement read. "There have been confirmed injuries."

One witness reportedly said she saw a girl get shot in the leg.

"I saw some girl, she got shot in a kneecap, I guess," the student told reporters. 

Another girl described the confusion she felt even after hearing the shots.

"I was sitting in my classroom and I heard really loud booms, and I didn't know what they were at first and then I realized what they were when I heard screaming," the girl said.

Students began to walk out of their classrooms and file out outside after authorities say a substitute teacher pulled a fire alarm when he realized there was a shooter in a bid to alert those on the large campus who did not hear the shots.

Aerial footage from the scene showed many students lined up outside the school, as law enforcement officials took some of their bags.

What appeared to be a figure covered in a white sheet could also be seen outside one of the school's exits.

President Trump tweeted about the shooting Friday, saying, "early reports not looking good. God bless all."