Howell Public Schools is closed today because of a social media threat, according to the district's website.
Michigan State Police alerted the superintendent to a message a Howell High School student received through Twitter from someone who threatened to shoot up the school.
Police are now investigating--and do not know if the threat is credible.
As a precaution, the superintendent has closed down the district for the day.
Howell Public Schools serves around 7,200 students.