It broke out on a freight train about seven miles from Calais. Fire fighters are still tackling the blaze
The fire broke out on a UK-bound lorry aboard the shuttle train at about 1400 GMT on Thursday, around 11km (7 miles) from the French entrance, the operator Eurotunnel said.
The French Interior Ministry said the lorry, which is understood to have overturned on the train, was carrying the chemical phenol, a toxic product used by the pharmaceutical industry.
A train was sent to collect the people from the service tunnel and take them back to France.
The Foreign Office said seven of those evacuated from the tunnel were British.
The French state train company SNCF said its services would not resume until Friday.
The tunnel carries Eurostar express trains between London, Paris and Brussels, as well as freight and passenger shuttles between Folkestone and Calais.
Traffic built up at the British end of the tunnel, with queues of lorries and cars tailing from the Eurotunnel terminal at Folkestone.
Motorists at the Channel Tunnel entrance were being given vouchers by staff to board ferries at Dover.
Eurolines, which is part of National Express, said it had capacity to take Eurostar passengers to Paris and Brussels by coach, via cross-Channel ferry services.
The Channel Tunnel has suffered several incidents since it opened to traffic in 1994 although only one - a fire in 1996 - caused serious injuries.
In August 2006, 34 people had to be led to safety after a fire broke out on a lorry being carried on a freight train.
The fire caused £200m worth of damage burned for over five hours, wrecking the concrete lining and facilities over about half a mile of tunnel.
Security exercises are staged in the Channel Tunnel by police, fire and ambulance services from both England and France to ensure preparedness for such incidents.