Bath holds a tragic place in Michigan history when farmer, tinkerer and Township treasurer, Andrew Kehoe, blew up the school killing a total of 44 people. 

The Bath School disaster is the deadliest act of mass murder in a school in United States history. It claimed more than three times as many victims as the Columbine High School massacre, half-again as many victims as the Virginia Tech and the Sandy Hook Elementary School shootings. It was the worst act of domestic terrorism in the United States until the 1995 Oklahoma City bombing. -Wikipedia

 

The Bath School disaster is described in Wikipedia as,

 On May 18, 1927, in what became known as the Bath School disaster, Andrew Kehoe, a farmer and local school board member angry over losing an election for town clerk and under notice for foreclosure, killed his wife, detonated bombs in his house and farm buildings, and at the same time set off a bomb in the consolidated school. He drove to the school in a truck rigged with more explosives, which he detonated next to the school superintendent. In all, Kehoe killed 44 people, 38 of them children, and himself, in the worst school murders in U.S. history. Only half of the 1,000 pounds (450 kg) of explosives set under the school went off, probably greatly lowering the death toll. Thirty-eight of the 314 students, three teachers, the superintendent, the postmaster, and a local farmer assisting at the scene were killed. Most of the dead were students from second to sixth grade. Fifty-eight others were injured.

Here is a video with interviews of some of the survivors.