BAYONNE, N.J. (CBSNewYork) — Public schools in Bayonne are closed Monday after officials said a threat was made on social media.

Just after 7 p.m. Sunday, authorities said they received the post “threatening to shoot up the various schools in Bayonne,” Police Chief Drew Sisk said at a news conference Monday.

“The initial Twitter message, tweet, was sent from an account that was activated that date and was deactivated by Twitter pretty much right on the heels of our investigation beginning,” Sisk said. “Subsequent to the initial Twitter posting, this morning we received a screenshot of a Snapchat image that had similar language and made what could be intimated as a similar threat.”

Also speaking at the news conference, Mayor Jimmy Davis said he is “very confident that our schools are safe” but said officials “took the extreme precaution of closing our schools.”

“The investigation is still ongoing as the police department could not confirm as of yet that this was a hoax,” he said. “We have decided that it was best to close our schools for today.”

Davis said local and state police as well the FBI are all assisting in the investigation.

“I assure you when we come up with the individual or individuals that are responsible for this, that they will be prosecuted to the fullest extent of the law,” said Davis.

In a letter posted on the district’s website, Superintendent Michael Wanko apologized for the late notice to parents, but said “we were hopeful that the post would be deemed non-credible by this morning, and school could be in session.”

In an earlier letter to parents Sunday on the district’s website, Wanko said the threat “stated that all Bayonne Public Schools will be shot up Monday morning.”

“Postings like this cause much anguish and concern for parents, students, and staff,” he said. “As information is shared with me regarding the investigations, I will notify everyone.”

Davis also posted a message on Facebook Monday morning saying police have been working to identify the source of the threat but said so far, police have “not been able to determine the source, and therefore rule out its credibility.”

“I will continue to update our residents as information becomes available,” he said.

Davis said Monday night schools will be open Tuesday.

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