A huge fire has broken out at a block of flats in Britain’s capital, London, after several explosions struck the block, witnesses say.

The fire ripped through flats of the 16-story building and damaged homes on the first and second floors in the Canterbury Gardens complex on Saturday.

More than 72 firefighters along with 10 fire engines were called to the area, according to the London Fire Brigade.

Witnesses said they heard an explosion before the fire broke out.

"We were having lunch and heard a small explosion and we saw a black cloud of smoke going up and the growing fire,” said one of the witnesses.

"Some seconds after the first explosion we heard one or two more, also small. There were some people in the field in front, I guess calling the emergencies," the witness added.

Some 50 people have been evacuated from the building. Three people, including a pregnant woman, a man, and a girl were taken to hospital suffering smoke inhalation.

Authorities have launched an investigation into the incident.