A parent notified the school of the posting, authorities said.

WEST PALM BEACH — A social-media posting shared with Forest Hill High School students and parents was investigated as a threat that was determined to be unfounded, a Palm Beach County School District spokeswoman said Friday.

In a message to parents, Forest Hill principal Mary Stratos said a parent notified school officials of a questionable photograph that was posted on SnapChat. Adults and students at the West Palm Beach school who had the "Air Drop" feature activated on their cellphones were able to receive the SnapChat posting as a text message.

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An investigation determined that there was no legitimate threat to the school, Stratos said. She did not describe the photograph in her message. A school district spokeswoman said no classrooms were evacuated.

However, Stratos noted that the incident "created a significant school disturbance and compromised school operations."

"I want to stress the importance of discussing with children that threats are no joke, and are taken very seriously," she said.