The collision happened shortly after 7am on the town's ring road at Sandelford Bridge over the River Bann.
The PSNI said a truck was in collision with a stationary vehicle and it then struck a man who was carrying out work on the carriageway.
Police are investigating the incident.
In Dublin, a ten-year-old boy died in hospital following a road accident yesterday afternoon.
The boy was cycling at Faussagh Road in Cabra when his bicycle was struck by a Dublin Bus vehicle shortly after 4.30pm.
He was taken to Temple Street Children's Hospital where he later died.
