An investigation is under way into the cause of a blaze which engulfed a polystyrene factory, causing nearby workers to flee the area.
Bedfordshire Fire and Rescue crews remain at the scene at Twinwood Business Park, in Milton Ernest, after being called at about midday on Friday.
Three buildings caught fire and at its height 60 firefighters tackled the flames.
Thick black smoke could be seen for miles around.
Thurleigh Road remains closed but other roads, including the A6, have reopened, the fire service said.
Water was pumped to the site from the River Ouse more than a mile away.
Matthew Smith, who was evacuated from his work close by, said as it looked so "dangerous" they "ran out the area as quickly as we could".
Bedfordshire Fire said "all people have been accounted for" and crews from Northamptonshire, Cambridgeshire and Oxfordshire attended.