Just before 8 a.m., a student shot himself in the men's restroom at Jackson Memorial, according to Jackson Township Police.
The school is about 55 miles south of Cleveland.
During a 2 p.m. news conference, authorities said a "distraction" device was found in the student's backpack.
A distraction device would be "something that could make some smoke, or make a bang," said the Jackson Township Police Chief. A bomb was not found, police said.
No other weapons were found, authorities said.
According to police, it's unknown if other students were involved and where the student obtained his weapon.