Around 1500 tonnes of metal are alight at a scrap yard in Dagenham, the night that London Fire Brigade is striking.
Up to 20 engines are at the scene, with 120 officers tackling the blaze, which began around 3.30pm.
The Fire Brigades Union has warned that "from 6.30pm (when the FBU strike starts) only 27 will be available in total throughout London."
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London Fire Brigade warned of "a lot of black smoke coming from the scrap metal fire in Dagenham. If you're in the local area close your doors & windows"