MILLBURY, Ohio - A tornado unleashed a "war zone" of destruction in northwest Ohio, destroying dozens of homes and an emergency-services building as a line of storms killed at least seven people and threatened to do more damage Sunday in the Midwest.

Storms collapsed a movie-theater roof in Illinois and ripped siding off a building at a Michigan nuclear plant, forcing a shutdown.

But most of the worst was reserved for a 100-yard-wide, 7-mile-long strip southeast of Toledo littered Sunday with wrecked vehicles, splintered wood, and family possessions.

The tornado ripped the roof and back wall off Lake High School's gymnasium about 11 p.m. Saturday, several hours before the graduation ceremony was to begin. The school board president said one of the victims was the father of the class valedictorian.

Two buses were tossed onto their sides and another was thrown about 50 yards, landing on its top near the high school's football field.

Lake Township Police Chief Mark Hummer flew over the damaged area and said at least 50 homes were destroyed and another 50 severely damaged, as well as six commercial buildings.

"It's a war zone," he said.

The tornado turned a building used by township police and emergency-medical personnel into a mishmash of 2-by-4 framing and pink insulation. Hummer was talking to a police dispatcher by phone when the storm hit.

"She started saying, 'The building is shaking,' and then another dispatcher came on and said, 'The roof just blew off," he said.

Those killed included a person outside the Police Department and a motorist, Hummer said. He said a young child and two other victims were from nearby Millbury, a bedroom community of 1,200 about 10 miles southeast of Toledo. Hummer said two other people died at hospitals, but he did not have details.

In southeastern Michigan, severe storms and high winds ripped siding off a building at the Fermi 2 nuclear plant, causing it to shut down automatically, said Dan Smith, the public-information officer for Monroe County.