According to the Telegraph, the French authorities were trying to stop the invasion and evict the refugees from the terminal, which led to the suspension of all passenger and freight services through the tunnel.
Eurotunnel said the tunnel had been closed as the security forces went in to try and track them down.
The spokesman said: “They ran through the terminal, knocking a few staff to the ground and throwing stones at them”.
The spokesman said: “It’s clearly an organised attack when it comes in such a large number, there are over 100 in this one group”.
The lorry driver climbed up to the space above the cab and pulled the migrant down after being alerted by the police officers.
A large number of refugees reportedly arrived in a well-organized manner, and about 100 of them managed to break into the terminal.
The area where the break-in occurred is now having high security fencing installed, Eurotunnel said. “Their determination and aggressiveness are growing”, a police source said.
A police source told AFP that earlier Friday evening there had been a substantial movement of migrants through Calais and towards the tunnel entrance “in the presence of No Border militants” – an activist group backing free movement in Europe.
Ten people, including seven migrants, suffered minor injuries during the storming of the tunnel, a firefighter at the scene said.
The incident was the latest in a series involving migrants who are camped around the northern French port of Calais in the hope of reaching Britain. At its peak, the number of attempts to board lorries or trains was around 2,000 a night, but that has since fallen.
Calais has always been an immigration flashpoint but in the past year has become part of a wider pan-European crisis, with states struggling to agree on how to handle inflows of people fleeing conflicts or poverty in the Middle East and Africa.