AN investigation has been launched after a motorcyclist died after colliding with another biker and a horse on the A31 last night.
The accident closed the road as well as the M27, causing traffic chaos across the area.
The road did not reopen until the early hours of this morning.
Both men were rushed to hospital but one died as a result of his injuries.
The other motorcyclist is still in a "serious condition".
The circumstances of the collision, which happened at 6.15pm, and how the horse came to be on the road are under investigation.
The man's next of kin have been informed of his death.
Hundreds of motorists were left trapped in their cars as the emergency services flooded the scene, half-a-mile east of Picket Post.
The crash happened an hour after the escaped horse had already brought traffic to a standstill.
Anyone who witnessed the incident should contact Eastleigh Roads Policing Unit by calling 101.