The crash happened at 12:41 p.m. on Newport Gap Pike, at Burnside Boulevard.
The vehicle had jumped a curb and struck trees and shrubs along the road. First responders found an elderly male driver unconscious behind the wheel.
The man and his female passenger, his sister, were both transported to Christiana Hospital. The man is in critical condition and his sister is being treated for non-life threatening injuries.
Police say initial reports from the scene are that the man may have been attempting to drive to a nearby fire department for help after suffering from a medical issue.
