As many as 10 people were killed in a shooting Friday morning at a high school south of Houston, law enforcement sources confirmed to CBS News. Two students and a school resource officer were shot and injured.
Another law enforcement officer was also injured but was not shot, CBS News has learned.
Harris County Sheriff Ed Gonzalez said a male suspect was in custody and a person of interest was detained and questioned. Both were believed to be students at the school.
"We hope the worst is over and I really can't say any more about that because it would be pure speculation," Assistant Principal Cris Richardson told media outlets at the scene.
School officials said law enforcement officers were working to secure the building "and initiate all emergency management protocols to release and move students to another location." Students from the high school were being transported to another location to reunite with their parents.
A parent told CBS affiliate KHOU-TV that some students were evacuated to an auto shop near the campus.
Tyler, a senior at the school, told KHOU-TV that his friend saw "some kid" with a gun. A fire alarm was pulled. When teachers and students were outside, shots were fired, Tyler said.
"As soon as the alarms went off, everybody just started running outside," 10th-grader Dakota Shrader told reporters, "and 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."
Tyler said he ran behind some trees, heard more shots, jumped a fence and ran to a car wash. He said he saw firefighters treat a girl who had a bandage around her knee and may have been shot.
One student told Houston television station KTRK in a telephone interview that a gunman came into her first-period art class and started shooting. The student said she saw one girl with blood on her leg as the class evacuated the room.
"We thought it was a fire drill at first but really, the teacher said, 'Start running,'" the student told the television station.
The student said she didn't get a good look at the shooter because she was running away. She said students escaped through a door at the back of the classroom.
Authorities have not yet confirmed that report.
In Washington, President Trump reacted to the shooting on Twitter. "School shooting in Texas. Early reports not looking good. God bless all!" Trump said.
Aerial footage from the scene showed students standing in a grassy field and three life-flight helicopters landing at the school in Santa Fe, a city of about 13,000 residents roughly 30 miles southeast of Houston.
According to a law enforcement official, the FBI was responding to offer assistance, CBS News senior investigative producer Pat Milton reports.
The U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives also said it was responding.
There was a large law enforcement response to the same school in February when it was placed on lockdown after students and teachers said they heard "popping sounds." Santa Fe police swept the campus but found no threat.
This story originally appeared on CBS News on Friday, May 18, 2018 at 12:45 p.m. ET.
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