At least two people died and 37 others were injured when about 200 vehicles crashed Wednesday in thick fog on a Michigan highway, police said.

One person also was killed in Indiana when at least 20 vehicles piled up amid heavy fog on a highway east of South Bend (search). Numerous others were injured.

The National Weather Service (search) had issued a dense fog advisory for the area, saying visibility could be less than a quarter mile.

In Michigan, a 14-year-old boy was killed when the sport utility vehicle he was riding in and about 10 other vehicles — including a tractor-trailer — crashed on Interstate 96 (search) outside Lansing Wednesday afternoon. The boy's mother and grandmother were in critical condition, Ingham County Sheriff Gene Wriggelsworth said.

The other fatal crash occurred about 30 minutes later when a man hit a semitrailer from behind, Wriggelsworth said. The victim was not immediately identified.

A total of 114 vehicles were involved in pileups in the eastbound lanes, while between 80 and 100 vehicles crashed in the westbound lanes, the sheriff's department said.

At least eighteen people were being treated Wednesday evening at a hospital in Lansing. State police closed a 12-mile stretch of the highway in both directions following the accidents. The eastbound lanes were reopened late Wednesday, but the westbound lanes remained closed.

David and Janet Morrow of South Bend, Ind., said their son, Christopher, called from his cell phone on I-96 and told them, "I'm standing here in the road and I'm not sure how I got here." He told his parents his car "folded up like an accordion" when it crashed.

The chain-reaction collision in Indiana left wrecked vehicles scattered Wednesday morning in both directions over a three-mile stretch of the Indiana Toll Road, state police Sgt. Rodger Popplewell said. Police closed a 43-mile stretch of the highway for more than six hours.

Popplewell said a man riding in a van was killed when the vehicle was caught between two tractor-trailers.

Two ambulances were also struck by semitrailers as paramedics treated injured drivers, Popplewell said. No emergency workers were hurt.

"Visibility was down to 20-25 feet," Popplewell said. "The fog would disappear and then reappear, so it caught motorists completely by surprise."

At least seven injured people were treated at hospitals in the Indiana crashes.