MASSILLON, Ohio — A seventh-grader who died a day after shooting himself inside a middle school restroom had fireworks and extra ammunition in his backpack, police said on Wednesday.

Investigators were reviewing cellphones and other electronics found at the boy’s home, but it was too early to know whether the shooting was intentional or if the 13-year-old had other plans, said Jackson Township Police Chief Mark Brink.

“We can make assumptions,” he said. “I’m not willing to do that.”

The boy shot himself on Tuesday just before classes began at Jackson Middle School, near Massillon, police said. No other students were injured.

He died at a hospital on Wednesday, according to the Summit County Medical Examiner’s Office.

The boy took the .22-caliber long gun from his mother’s house and managed to conceal it under his clothes while he rode a bus to school, Brink said. Others who saw him that morning didn’t notice he was hiding anything.

Investigators looked through his backpack after the shooting and found bottle rockets, batteries and ammunition, Brink said. He earlier described the items as devices meant to cause a distraction.

He also said the investigation so far has not uncovered any warning on social media.

Some parents complained that they waited hours before they could take their children home, but Brink said authorities first needed to make sure the building was safe because “we didn’t know exactly what we were dealing with.”

Classes resumed on Wednesday.