LA PORTE COUNTY, Ind. — A driver was killed Thursday night after Indiana State Police said they crashed into the back of a semi-truck parked on the shoulder of Interstate 94 in La Porte County.

ISP Trooper James Brasseur said the driver, who hasn’t been identified, ran off the road around 10 p.m. on I-94 eastbound near Michigan City and struck the back of the trailer.

It’s not yet clear why the driver ran off the road, according to a preliminary investigation by Trooper Kevin Council.

The driver of the semi-truck wasn’t injured.