Police responded to almost a dozen schools Monday after threats circulated on social media, although investigators later tracked the source to Queens.

In a Snapchat screenshot, the message reads, "I'm going to shoot up the school March 5...Please save yourself." It warned the attack would happen at 12:27 p.m.

Police say it originated on Feb. 27 at Hillcrest High School in the Jamaica neighborhood of Queens.

The NYPD is now investigating, but Suffolk police had to respond to schools in Brentwood, Central Islip, West Islip, North Babylon and Sayville. The threat prompted lockouts and lockdowns across the Island.

"We've seen a dramatic increase in school threats since the Florida Parkland shooting," says acting Suffolk Police Commissioner Stuart Cameron. "We cannot fail with respect to investigating every single school threat. I'm personally made aware of every single one of them."

Authorities say students should refrain from making such threats, even as a joke.

"It's very serious," Cameron says. "You don't want to ruin your future by getting arrested for something called 'making a terroristic threat.'"