An online threat against staff and students at Ottawa’s Carleton University from a Twitter account that has posted photos of guns and bombs rattled nerves on campus before police determined the threat was not credible.

A tweet, sent early Monday from a now-suspended account read, “Tomorrow morning I will be taking many lives at Carleton University. Take this as a warning, if you go to campus you will be among the casualties.”

“The initial investigation revealed that the threats are not credible and that there is no known risk to public safety,” Ottawa police Sgt. Steven Desjourdy wrote in a media release on Monday. “It is safe to attend the campus and it remains open.”

Police believe the threat originated in the U.S. Desjourdy said an investigation into the incident remains open and Ottawa police are cooperating with “international partners” to determine the message’s origin.

“We do have a person and a jurisdiction,” he told CTV Ottawa on Monday. “At this point, it is only speculation. It is under investigation. I can’t share that information.”

The Carleton University campus was more quiet than usual on Monday due to the Victoria Day holiday. Students living on campus and attending meetings were no less concerned about the threat.

“It was a little scary, because you wouldn’t think something like that would happen here. But it is totally possible,” said Carleton student Danielle Ben-Shoshan.

The university sent a message to all staff and students on Monday informing them about the threat and police involvement, and to confirm the campus would open as usual on Tuesday morning.

With a report from CTV Ottawa’s Joanne Schnurr