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.

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.

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.

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