The collision involved five vehicles and occurred shortly before 12.10pm, prompting police to close the road between Hayling Avenue and Tangiers Road in Portsmouth.
The van was travelling north on the Eastern Road when it collided with another vehicle. It then collided with several oncoming vehicles before rolling over onto its side.
Firefighters were seen providing emergency first aid to the victims of the collision; no life-threatening injuries are believed to have been sustained at this time.
The road is expected to be closed for some time while police conduct a full accident investigation and recovery agents work to clear the vehicles.