CHARLES COUNTY, Md. (WJZ) — A 13-year-old Maryland boy has been arrested after authorities say he posted on social media threatening to shoot students at a school.

The teenager, whose name has not been released, faces charges of making a threat of mass violence.

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The investigation began on Sunday, when the Charles County Sheriff’s Office got a tip about a suspicious post on social media.

Investigators found a post that included a photo of a gun and ammunition, along with a caption that indicated students at Milton Somers Middle School were going to be shot.

The sheriff’s office quickly identified the 13-year-old suspect, who was a former student at the school.

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After a search of the suspect’s home, investigators found that the gun in the social media post was at a friend’s house.

Officers searched that home, and were able to recover a starter pistol and 49 rounds of blank ammunition.

The sheriff’s office says the starter pistol looks and sounds like a real gun, but the blank ammunition meant it was unable to be fired.

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