Police identified the deceased Saturday as 59-year-old Clark Gibbs of Coatesville.
It happened around 9:30 p.m. Friday on the Route 30 bypass westbound near Route 340 in Caln Township, Pennsylvania.
Three victims were taken to Paoli Hospital for serious injuries, and a fourth was taken to Brandywine Hospital for moderate injuries.
The Route 30 bypass was closed in both directions between Route 340 and Reeseville Road, but has since reopened.
Pennsylvania State Police are investigating, and DUI is suspected.