A tractor-trailer crashed into an overloaded bus carrying members of an Amish church, sending at least 14 people, including a number of children, to a hospital in nearby Ann Arbor.
Most of those injured suffered cuts and bruises, while six people were in serious condition. Injuries were not believed to be life-threatening, police said. The 13-seat bus was carrying 22 people.
The bus driver swerved left to avoid a slower vehicle entering southbound U.S. 23 and clipped the front of the semitrailer, said State Trooper Randy Phare. The bus turned onto its side and skidded to a stop along the highway in Northfield Township, about 40 miles west of Detroit.
Another vehicle then crashed into the back of the stopped truck.
Alcohol or excessive speed were not factors in the crash, police said. But authorities were looking into the possibility of charges against the bus driver, said Phare, who wasn't sure whether those aboard the bus were wearing seat belts.
"It could have been a lot worse," he said, pointing to the truck's size and speed. He estimated the truck was traveling between 60 mph and 70 mph. The speed limit on that stretch of highway is 70 mph.
The bus passengers, members of a Mount Pleasant-area church, were headed to a funeral in Ohio, Phare said.
Traffic was stopped along the highway as emergency workers treated the injured. All of the injuries were on the bus, police said.
Four adults and two children were in serious condition at the University of Michigan Hospital in Ann Arbor, spokeswoman Kara Gavin said.