Extra police were at Stillwater Area High School Friday after a threat of a shooting circulated online Thursday night.

A student who attends the school in Oak Park Heights posted the threat on social media, said Oak Park Heights Police Chief Brian DeRosier.

The threat on Snapchat indicated that “somebody would shoot up the school” on Friday.

Police learned of the threat around 8 p.m. Thursday. With the help of a school resource officer, police were able to identify a suspect. The parents of the student who had made the post also cooperated with the investigation “to allow us to quickly alleviate the concern over the threat,” the chief said.

As authorities continue to investigate, classes went on as scheduled.

“After a thorough investigation in cooperation with local law enforcement we are confident there is no existing threat to our students,” said a statement from the district that was sent to families early Friday. “We are taking extra measures to ensure a safe environment will be provided for our students and staff today, but it is always the choice of families as to whether to send children to school.”

The district did not disclose the nature of the threat.

In the statement sent to families on Friday morning, the district said it was grateful to law enforcement for “working swiftly to investigate the situation” and that district officials decided go ahead with classes.

DeRosier said police were on campus Friday to provide a “calming effect.”