Westbound I-94 reopened Tuesday afternoon east of U.S. 421 in LaPorte County following a crash that had shut down the busy stretch of highway for four hours, according to the Indiana Department of Transportation.

At 7 a.m. Indiana State Trooper Brandon Lankford was called to a crash where a tractor pulling a lawnmower had been struck by a vehicle on westbound I-94 at the 26.6 mile marker. Preliminary investigations showed that the tractor driver, a 68-year-old Winamac man, was heading east along the north ditch of the interstate, Indiana State Police said. 

The tractor could not mow farther because of the bridge at the 26.6 mile marker, causing the man to drive into the westbound lanes to attempt a U-turn to go back west along the same shoulder. 

The tractor driver failed to yield to a white 2004 Ford van that was in the left lane, and the vehicle collided, with the van unable to avoid the tractor, police said. 

The driver of the mower was flown out from the scene for medical care at South Bend Memorial Hospital. 

The driver of the van, a 27-year-old Michigan City man, was in good condition, police said.

ISP said drugs or alcohol are not believed to be a factor in the crash. 

All westbound lanes of the highway were closed for four hours Tuesday morning and traffic was being diverted onto U.S. 421 while the crash investigation was underway, officials said.

The crash remains under investigation. 

Times staff writer Anna Ortiz contributed to this story.