UPDATE - At least 10 killed in Texas school shooting

ADDS DETAILS THROUGHOUT, EDITS HEAD AND SUBHEAD TO MATCH DEVELOPMENTS

By Michael Hernandez

WASHINGTON (AA) - At least 10 people were killed and 10 others injured in Texas on Friday after a gunman armed with a shotgun and a .38-caliber revolver opened fire at the Santa Fe High School.

The shooting at the school outside of Houston is "one of the most heinous attacks that we've ever seen in the history of Texas schools", Texas Governor Greg Abbott told reporters during an afternoon news conference. Two of the injured are in critical condition, he said.

Galveston County Sheriff Henry Trochesset identified the suspect in a statement as 17-year-old student Dimitrios Pagourtzis.

The suspect did not legally possess the firearms he allegedly used, Abbot said. They belonged to the suspect's father, and it was not immediately clear if the father knew his son had taken them.

Abbott said information from the suspect's journals and computer suggest the suspect sought to kill himself, but he could not as police moved in.

The suspect is being held at the Santa Fe Police Department.

Two additional individuals have been taken into custody as persons of interest. One was apprehended at the scene.

An officer with the Santa Fe Independent School District was injured during the shooting, Harris County Sherriff Ed Gonzalez said.

The school district confirmed "possible explosive devices" have been found at the school and off campus, and said police are in the process of disarming them.

"Do not touch any items out of place and call 911 as we have agencies that can respond. Our thoughts and prayers are with our students, staff and our community," the school district tweeted.

Officers are currently operating under the assumption that Pagourtzis made the explosives, according to Abbott, who said one of the recovered devices was a molotov cocktail and another was a carbon dioxide device.

The school has been evacuated.

Addressing reporters at the White House, President Donald Trump said America's epidemic of school shootings "has been going on too long in our country".

"We grieve for the terrible loss of life and send our support and love to everyone affected by this absolutely horrific attack," he said. "May God comfort the wounded and may God be with the victims and with the victims' families."

Pagourtzis is being held on capital murder charges without bond.

There have been at least 22 school shootings in the U.S. this year alone, according to CNN.

This story is developing.