The injured were treated in a service area while other lorry drivers were evacuated on a Shuttle train travelling towards France. A spokeswoman for Eurotunnel said the fire had started on a lorry being taken from France to England. Firefighters managed to extinguish the blaze.
The fire was near the French end of the tunnel and everyone had been taken out safely. "Only one of the injured is causing concern," said the spokeswoman. She said the fire had caused a great deal of smoke.
"We do not know exactly what damage has been caused because the firefighters are still dealing with it."
Emergency services were standing by at the Kent end of the tunnel in case they were needed.
Kent Fire Brigade sent its specially trained units along the service tunnel to help the French fire fighters.
A spokesman said: "The fire was 31km [19 miles] from the UK end of the tunnel. We have 17 fire appliances standing by in case they are needed."
Two senior fire officers were being flown in an RAF Sea King rescue helicopter across The Channel to France. They left shortly after midnight. The helicopter, based at RAF Wattisham in Suffolk, picked up the two officers from Shorecliffe Barracks near Dover and was due to land with them near the Calais entrance to the tunnel. The Eurotunnel spokeswoman said later that the train would have been carrying about 30 passengers, mostly lorry drivers.
There were reports that hazardous materials were being transported on the freight shuttle, but no details were immediately available.
Fire in the Channel Tunnel is the main fear of both passengers and operators. Eurotunnel says it follows a strict set of measures to make its entire operation as risk-free as possible including Shuttle train wagons that are fireproof and have fire detection systems, various firefighting equipment on shuttles including handheld fire extinguishers and automatic foam systems for dealing with fires under vehicles caused by leaking fuel.
In addition, there would be a halon gas fire suppression system to which evacuees would be safely exposed for some time and closed-circuit television cameras to monitor the interior of all shuttle wagons throughout the journey.
Eurotunnel stressed that clear instructions on emergency procedures would have been given to passengers on boarding the shuttles.