Students at Mount Vernon High School were evacuated Tuesday after a bomb threat, according to officials.
The school district's superintendent says the bomb threat was a false alarm.
Students and staff were allowed to re-enter the building around 3 p.m.
Emergency personnel had been inside the building searching for any bomb-like devices.
The school superintendent said the bomb threat was made before 1 p.m. but did not say how or in what fashion that warning came through.
The district immediately instructed everyone to immediately evacuate the building and ended the school day early.