BORDEN, Ind. -- A minivan crossed the center line of Indiana 60 and struck an oncoming school bus that contained no children on Monday afternoon, killing the minivan's driver, police said.

Sherri L. Anderson, 36, of Pekin, was pronounced dead at the wreck site in southern Indiana's Clark County, state police said.

The driver of the West Clark Community Schools bus, Anna Marie Klein, 66, of Floyds Knobs, was slightly injured and was taken to Floyd County Memorial Hospital, police said.

Police said Anderson was driving west in her 2008 Dodge Caravan shortly before 4 p.m. Monday when she crossed Indiana 60's center line and hit the eastbound bus.

Authorities said they didn't know why the minivan went into the eastbound lane.

Anderson was alone in the van. Police said they didn't know whether she or Klein were wearing seat belts.