A tractor-trailer slammed into the back of a packed minivan in northern Indiana late Thursday, killing at least seven people and sending four others to hospitals, authorities said. The minivan was carrying 10 people when it was hit along the Indiana Toll Road near Bristol, just south of the Michigan border, according to Indiana State Police. Witness accounts suggest that the minivan may have hit a deer, then slowed or stopped in the eastbound lanes before it was hit from behind by the tractor-trailer, police said.