County Road 50, just north of Campbellford is closed for a police investigation.
Northumberland OPP, paramedics and the Trent Hills Fire Department were called just before 1 p.m. on Monday for a fatal single vehicle collision.
Police say an SUV that was travelling north failed to negotiate a curve north of Meier Street and went into the ditch.
The passenger died as a result of the collision and the driver was taken to a nearby hospital but is expected to be taken to a trauma centre in Toronto with serious injuries.
County Road 50 is currently closed between Church Street and 10th Line West, while OPP members trained in collision reconstruction measure and document the scene.
The closure will remain in place for several hours while police investigate.
The cause of the crash remains under investigation.
Information will be updated as it becomes available.
