Two students suffered injuries and were receiving medical care, FOX4 Dallas-Forth Worth reported. No updates on their conditions were immediately available.
The suspected shooter was taken into custody, police said, without elaborating further.
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Lamar High School in Arlington, Texas, was put on lockdown early Monday after a shooting was reported outside the school building, police said. (Google Street View, File)
Police did not immediately share whether any injuries were reported, saying more information would be released later.
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Students and staff will be sent home once the lockdown is lifted, Arlington school district officials said, according to WFAA-TV.
Arlington is located about 28 miles west of Dallas.
This is a developing story; check back for updates.