The Oakley Police Department had an increased presence at Freedom High School on Wednesday due to threats that had been directed at the school via social media, according to a letter to parents posted on Facebook.
Principal Kelly Manke said police had an "all hands on deck" attitude, also thanking the FBI and prosecutors for their assistance in the investigation.
"Going forward, we will continue enhanced police presence until the perpetrator is identified to help our school community feel safe during this unsettling time," Manke said in a statement.
The school has taken a number of security measures in recent years by locking classroom doors during class and adding security cameras. Faculty and staff also participate in active shooter trainings.
School officials did not provide details about the nature of threat, but said it was received via Snapchat.