Ten people have been killed and 10 others injured after a shooting by a student at a Texas high school, says the state governor.
The attacker, who is in police custody on murder charges, was identified as Dimitrios Pagourtzis, a 17-year-old pupil at Santa Fe High School.
The suspect allegedly used a shotgun and revolver apparently taken from his father, who legally owned the weapons.
Most of the dead from the attack in Santa Fe are students, said police.
Texas Governor Greg Abbott said “various kinds of explosive devices” had been found at the school, 40 miles (65km) south of Houston, and off-campus.
These included “a CO2 device” and “a Molotov cocktail”, he added.
The Republican governor said police had found information on the suspect’s diary, computer and mobile phone suggesting he planned the attack.
Mr Abbot said the teenager wanted to take his own life afterwards, but “gave himself up” because “he didn’t have the courage to commit the suicide”.
Santa Fe Police Chief Jeff Powell advised residents to be aware of any suspicious objects they find.
“Do not touch any items that look out of place,” he said.
Santa Fe school police officer John Barnes has been named among the injured. He was in a critical condition and undergoing surgery, according to local media.
How the attack unfolded
Students said the shooter entered an art class and opened fire shortly before 08:00 local time.
“There was someone that walked in with a shotgun and started shooting,” one witness told KTRK-TV, “and this girl got shot in the leg.”
One student told local network KHOU-11 that a teacher who realised what was happening activated a fire alarm to evacuate the building.
Dakota Shrader, a student, told CBS News that everyone began running outside when the alarms went off.
“Next thing you know everybody looks, and you hear boom, boom, boom, and I just ran as fast as I could to the nearest floor so I could hide, and I called my mom.”
Another student, Damon Rabon, told CBS he looked out of his classroom after hearing loud bangs and saw the shooter.
“Black trench coat, short kind of guy, had a sawed-off shotgun,” he said.
There were 1,400 students in the school at the time of the attack, according to Lt Gov Dan Patrick.
What’s the reaction been?
President Donald Trump, speaking at a prison reform event at the White House, described the attack as “absolutely horrific”.
“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,” he added.
He ordered flags to be flown at half-mast at the White House and all public and military buildings.
Two weeks ago, the US president reiterated his call to arm teachers with guns during a speech in Dallas to the National Rifle Association.
Governor Abbott said it was “one of the most heinous attacks that we’ve ever seen in the history of Texas schools”.
“It’s impossible to describe the magnitude of the evil of someone who would attack innocent children in a school.”
First Lady Melania Trump tweeted: “My heart goes out of Santa Fe and all of Texas today.”
Shortly after the shooting began in the town of about 13,000 residents, a man carrying an American flag, wearing a Trump hat, and carrying a pistol on his hip approached news cameras.
The man, who did not give his name, told reporters his goal was to “make America great again”.
How do previous school shootings compare?
The Texas attack is the deadliest school shooting since the one in February at Parkland, Florida.
That assault left 17 dead and spawned a nationwide youth-led campaign for gun control.
Earlier this week, a police officer was able to stop a former student who opened fire at an Illinois high school before anyone was injured.