George Mason University "inadvertently" warned students about an armed person on campus on Tuesday morning. There is no threat, the Northern Virginia school quickly said in a follow-up message.
The frightening warning appeared on the school's official Twitter account: "A person with a weapon is on the Fairfax campus and considered dangerous. Take shelter in a safe location and lock/block door. Defend yourself if necessary. Avoid campus."
The 10:45 a.m. tweet was deleted. At 10:50 a.m., a new tweet said: "Mason Alert:There is no emergency at George Mason University. This message was inadvertently sent. See email for more information."
The school sent a campus-wide email at 10:45 a.m. with an initial sentence describing an emergency, followed by a sentence saying it was only a test.
The school's safety director apologized for the false alarm and said a company the university works with accidentally sent the alerts.
"The message was sent inadvertently by one of the university’s emergency notification system software vendors. It was not initiated by anyone on our campus," David Farris said in a letter to students and staff.
"We understand that this was a frightening experience for our community and apologize for the fear it may have caused," Farris continued.
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The safety director did not name the company. The university will determine how the message was sent and make sure it doesn't happen again, he said.
The scare comes a day before freshmen are set to move in on Wednesday.
A similar incident occurred last year at Montgomery College.
Stay with News4 for more details on this developing story.