SANTA FE, Texas (AP) — A 17-year-old armed with a shotgun and a pistol opened fire at a Houston-area high school Friday, killing 10 people, most of them students, authorities said. It was the nation's deadliest such attack since the massacre in Florida that gave rise to a campaign by teens for gun control.

The suspected shooter, Dimitrios Pagourtzis, who was in custody on murder charges, also had explosive devices that were found in the school and nearby, said Gov. Greg Abbott, who called the assault "one of the most heinous attacks that we've ever seen in the history of Texas schools."

Investigators offered no immediate motive for the shooting. The governor said the assailant intended to kill himself but gave up and told police that he did not have the courage to take his own life.

The deaths were all but certain to re-ignite the national debate over gun regulations, coming just three months after the Parkland, Florida, attack that killed 17 people at Marjory Stoneman Douglas High School.

"It's been happening everywhere. I've always kind of felt like that eventually it was going to happen here, too," Santa Fe High School student Paige Curry told Houston television station KTRK. "I don't know. I wasn't surprised. I was just scared."

Another 10 people were wounded at the school in Santa Fe, a city of about 13,000 people roughly 30 miles (48 kilometers) southeast of Houston, the governor said. The wounded included a school police officer who was the first to confront the suspect and got shot in the arm.

Hospitals reported treating a total of 14 people for injuries related to the shooting.

Michael Farina, 17, said he was on the other side of campus when the shooting began. He heard a fire alarm and thought it was a drill. He was holding a door open for special education students in wheelchairs when a principal came bounding down the hall and telling everyone to run. Another teacher yelled out, "It is real!"

Students were led to take cover behind a car shop across the street from the school. Some still did not feel safe and began jumping the fence behind the shop to run even farther away, Farina said.

"I debated doing that myself," he said.

The gunman yelled "Surprise" before he started shooting, according to Texas Rep. Michael McCaul, the chairman of the House Homeland Security Committee.