THICK smoke was seen billowing out of a 20-storey housing block as firefighters rushed to the scene on Sunday.

The London Fire Brigade used a special aerial ladder brought in from its station in Soho to reach the upper floors at the building in Bath Street, Clerkenwell. One woman was treated at the scene for smoke inhalation by paramedics.

Around 50 people left the building before crews arrived.

The brigade said they believe the blaze, which burned on the 16th and 17th floors, had begun accidentally, although the exact cause remained “undetermined”.

Station commander Keith Carmichael, who was at the scene, said: “There was a lot of thick smoke issuing from the building when crews arrived, which prompted a high number of calls to our 999 control officers. Our aerial ladder was used initially to tackle the blaze from the outside as crews made their way up to the fire floor inside.”

He was joined by 70 firefighters from six different stations. They were called out at around 5.40pm and the fire was under control by shortly after 7pm.