The Texas student charged in the school shooting at Santa Fe High School posted an image on Facebook of himself wearing a "Born to Kill" shirt and used his father's shotgun and pistol in the attack that left 10 dead and 10 wounded, authorities said Friday. A motive wasn't immediately clear for the nation's deadliest attack since February.

The suspect, 17-year-old Dimitrios Pagourtzis, was held without bond in the Galveston County jail on charges of capital murder, said the county sheriff, Henry Trochesset. Gov. Greg Abbott said both weapons were owned legally by the suspect's father.

It was not clear whether the father knew his son had taken them. Authorities urged parents nationwide to lock away their guns to keep them away from children.

Abbot said at a news conference that "unlike Parkland, unlike Sutherland Springs, there were not those types of warning signs." He was referring to the Feb. 14 school shooting in Florida and one in November inside a church in a town near San Antonio. Abbott said the early investigation showed no prior criminal history for Pagourtzis — no arrests and no confrontations with law enforcement.

"The red-flag warnings were either nonexistent or very imperceptible," Abbott said, though he acknowledged Pagourtzis had recently posted a picture of a T-shirt reading "Born to Kill" on his Facebook page.

That same Facebook profile described Pagourtzis as planning to enter the U.S. Marine Corps next year, but the Marine Corps told The Associated Press it has reviewed its records and found no one by that name as either a recruit or a person in their delayed entry pool.

Classmates described Pagourtzis as quiet, an avid video game player who routinely wore a black trench coat and black boots to class. He had played football on the school's junior varsity squad and danced as part of a church group. Those who know him expressed shock he might be involved in the killings.

In addition to Pagourtzis, a second person has also been detained, said Harris County Sheriff Ed Gonzalez.

The school went on lockdown at 8 a.m. An unknown number of possible explosive devices were found at the school and at a separate site nearby.

A woman who answered the telephone at a number associated with the Pagourtzis family declined to speak with the AP.

"Please don't call us. Give us our time right now, thank you," she said.

Tristen Patterson, a 16-year-old junior at Sante Fe, considered Pagourtzis a friend. He said Pagourtzis was into video games that simulated war, and that he sometimes talked about guns — firearms that he liked or wanted to get. "But he never talked about killing people or anything like that," Patterson said.

He said Pagourtzis didn't show signs of being bullied but also rarely talked about himself. In one of their classes, Pagourtzis would sometimes enter the room "acting a little bit down or sad. A little bit sluggish," Patterson said.

"But he never talked about why," he said.

Father Stelios Sitaras of Assumption of the Virgin Mary Greek Orthodox Church in Galveston, Texas, said he met Pagourtzis when the young man danced with a group as part of an annual festival in October. He said the Pagourtzises are members of a nearby parish.

Sitaras said he had never heard of the teen being in any sort of trouble.

"He is a quiet boy," the priest said. "You would never think he would do anything like this."

Michael Farina, 17, said he grew up with Pagourtzis and would play video games with him. He said Pagourtzis knew a lot about guns and remembered him asking which one he should get when he was older.

"I'm kind of dumbfounded. We didn't get any warning," Farina said.

He said a black trench coat and black boots was Pagourtzis's regular outfit to school. "I guess you could say it was his kind of style," Farina said. He said he wasn't someone who got into trouble and described him as a "run of the mill" student.

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Biesecker and Horwitz reported from Washington. Associated Press writers Eric Tucker in Washington, Paul J. Weber in Austin, Texas, and John Mone in Santa Fe, Texas, contributed.

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Follow Biesecker at http://twitter.com/mbieseck and Horwitz at http://twitter.com/JeffHorwitz

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