The southbound lane of the A11, near Barton Mills, is now open again and firefighters remain on scene following the blaze at the Esso station at Barton Mills.
Suffolk Fire and Rescue Service were called to the Fiveways roundabout at just after 6.50am today after a fire broke out at the Esso service station.
Four fire engines - from Bury St Edmunds, Mildenhall and Newmarket - and a water carrier attended the blaze which is believed to have started in a refrigerator unit.
Although the fire was under control by 10.46am, three fire crews were still on the scene as of 4.15pm Saturday afternoon, including a fire investigation unit.
A structural engineer is also on scene to look at the building.
MORE: Worker acted quickly to stop fire spreading at service station on the A11 at Barton Mills
Area fire commander Nigel Vincent from Suffolk Fire and Rescue Service said: 'The first attending crews quickly isolated the forecourt so that means basically they cut all the electricity supply off to the forecourt which renders the pumps unable to draw petrol from the tanks underground which isolates the petrol supplies on site away from the fire.'
It is believed the fire may have started at a fridge unit.
The A11 was closed in both directions between the B1085 and the A1065 at Mildenhall, but both northbound and one southbound lane were reopened at 9.15am.
The remaining southbound lane was reopened at 4.30pm.
The area around the Barton Mills roundabout is one of the busiest sections of road in East Anglia.
Thousands of vehicles a day use the road and many people will be heading in and out of the region as the Easter holidays get into full swing.
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