The collisions took place on the A3 close to Petersfield, shortly after 9.15am.
The severity of the incident has closed the B2070 Buriton junction, northbound.
As of 1pm this afternoon, the route was still closed, with diversions in place, a police spokesman said.
Hampshire Constabulary is now warning people to drive carefully, particularly when in heavy rain.
A statement from the force on its official Facebook page said: ‘We would also like to take this opportunity to remind motorists to drive to the conditions following this morning's rain.
‘Take extra care and allow yourself plenty of room from the vehicle in front.’
Updates to follow.