Three adults and two children lived in the two-story farmhouse just outside city of Fostoria, said Dean Henry, a spokesman for Seneca County.
The identities and ages of those killed were not released. Authorities said the first 911 call came early yeserday from a girl inside the home who was using her father's cellphone.
Crews found three bodies in the morning and two more bodies later beneath some of the rubble. Parts of the house had collapsed, making it dangerous and difficult to search, Henry said.
Nothing was left of the home's roof or front porch, and much of both floors were badly burned. The cause wasn't known yet.