LINCOLN, Neb. (AP) — Authorities say a Lincoln high school was briefly placed on lockout status after a home-schooled prankster posted a vague threat to "shoot up" the school on Twitter.

The Lincoln Journal Star reports that the tweet was traced a 17-year-old boy. Lincoln East High School was placed on a lockout Wednesday afternoon.

Police later concluded the tweet was intended as a joke. They forwarded their reports to the Lancaster County Attorney's Office to determine if the teen should face prosecution.

Authorities initially suspected a former East High student, based on a small Twitter picture that captured only part of the account holder's face. Police spotted that person walking on school grounds with a guitar case, but later ruled him out after discovering he didn't have a weapon or a Twitter account.

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Information from: Lincoln Journal Star, http://www.journalstar.com