Police are currently on the scene of the crash on the A354 Weymouth Relief Road between Stadium Roundabout and Monkton Hill.
The road is currently closed to allow emergency services to respond to the incident.
A spokesperson for Dorset Police said: “Officers have closed the A354 Weymouth Relief Road between the Stadium Roundabout and the Jurassic Roundabout following a three-vehicle road traffic collision. Monkton Hill is also closed.
“Motorists are asked to avoid the area while emergency services respond to the incident.”