Some parents went to school to pick up their children and said they were hearing from inside the building that this might be related to a threat of violence related to a pep rally that was scheduled for 11 a.m.
Bristol Central High School was on lockdown on Wednesday morning over what was called a Columbine-like threat. The administration also canceled the school's pre-Thanksgiving Day pep rally.
"In collaboration with the Bristol Police, school administration uncovered a serious and potentially credible Columbine lie threat by an individual student," Principal Peter Wininger said in a statement on the school's website.
The threat was reported by three other students, Wininger said.
The threat was made in a post on Facebook, according to police.
Students said the post included two kids with guns and a comment saying something like "Getting ready for the pep rally."
Some parents who went to school to pick up their children said the rally was for the Thanksgiving football game between Bristol Central and Bristol Eastern.
Someone was taken away in an ambulance, but the lights were not on, so it did not appear to be an emergency situation. The lockdown began at 9:50 a.m and students were in locked classrooms with faculty and staff supervising and were safe, school officials said.
State police K-9 units searched the school for potential threats, but found nothing.
School was dismissed at 12:11 p.m., as was previously scheduled.
No arrests have been made. Police are continuing to investigate.