Around 20 firefighters are tackling a blaze close to the National Archives. London Fire Brigade said two disused water towers which were in the process of being decommissioned caught fire in Kew, south west London, at about 12.30pm.
Both towers are now "100% alight", a fire service spokeswoman said. A Scotland Yard spokesman said: "No-one is trapped or injured."
Police, who were called at 12.37pm, are providing assistance at the scene, he added.
More top news
Michael Danaher, 50, killed book dealer Adrian Greenwood at his home over a £50,000 first edition copy of Wind In The Willows.
The former Cardiff South and Penarth parliamentary candidate joins Suzanne Evans, Paul Nuttall and Raheem Kassam in the race.
From unnecessary X-rays to misguided blood tests, here is the full list of treatments health experts say will not improve your health.