By Amber Murray Source: PA Around 100 firefighters are tackling a blaze in the roof on London’s Somerset House. A spokesman said: “Fifteen fire engines and around 100 firefighters have been deployed to a fire at Somerset House. “Crews are tackling flames located in part of the building’s roof. Two of the brigade’s 32m ladders have been sent to the scene to support firefighting operations. “The entire site at Somerset House is now closed to the public whilst we tackle the fire. Traffic in the surrounding area will be impacted as crews respond. “The cause of the fire is not yet known.” Fire ward…