GRAPEVINE (CBSDFW.COM) – School administrators and police in Grapevine are praising the actions of some high school students who reported a social media post showing a gun on campus.

Monday morning, counselors will be on hand at Grapevine High School to talk to students following the incident on Friday afternoon. It happened around 1:30 in the afternoon, when a post surfaced on the social media site Snap Chat, showing a teen with a gun in his waistband in the school cafeteria.

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Administrators say some students immediately notified a teacher and administrator – and another student went to the school resource officer.

The school was placed on lockdown as police swept the building and took the suspects into custody without anyone hurt.

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Hearing that someone brought a gun onto campus was nerve-racking for some parents.

“Scary. It scared the living daylights out of me, especially when I read his texts and he stopped responding and stopped reading. So it’s a scary situation,” said Jennifer Jones, whose child attends Grapevine High.

The Grapevine-Colleyville ISD superintendent praised the bravery of the students who saw something and said something to authorities.

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Four teens face criminal charges, including making a terroristic threat, possession of a weapon, and trespassing.