ROCKVILLE, Md. (AP) — Authorities in Maryland are trying to figure out how an active shooter warning was sent out in error on a college campus.

The Washington Post reports that the warning went out Friday at Montgomery College in the Washington suburbs.

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The message was broadcast on Twitter and declared: “EMERGENCY! Active shooter at (insert campus) Campus. LOCK DOWN NOW. Go to nearest room and lock door! Follow instructions from authorities.”

The tweet was taken down about 25 minutes later. The school tweeted that there was no threat.

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The message had led to some panic and confusion online as people tried to learn if it was real.

School spokesman Marcus Rosano said the “false alarm” is being investigated.

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