The Simsbury Police Department was alerted about the potential threat on Thursday.
Several students reported the online post to the School Resource Officer and Simsbury High School staff when they arrived to school that morning.
Officials say the threat was not specific to Simsbury schools and that it was vague in its content.
The high school activated a “Lock Out” procedure and there was additional security on campus grounds.
Police say an investigation determined that the social media posting has been part of a nationwide hoax facilitated using social media throughout the country.