Gwyn Williams was over taken by the ambulance shortly before the crash in the New Forest and told ITV Meridian what he saw.
He had been driving along the A336 between Brockenhurst and Lyndhurst in the New Forrest.
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Tuesday afternoon's forecast for the west of the region
Tuesday afternoon's forecast for the east of the region
Forecasts show around 480,000 people are to move through Gatwick airport over Easter period.