Delaware state police say David Hinson and Michael Caldwell either committed or attempted to commit carjackings by rear-ending drivers to lure them out of their cars.
Investigators say a woman was sexually assaulted in one of the carjackings last Friday, then forced out of her car in Chadds Ford.
Police say Hinson and Caldwell were arrested after they switched cars, then caused a collision on I-95 southbound and Concord Pike.
Mahkiya Powell and Tonnaire McNair-Matthews were arrested on Monday in connection with the crime spree.