Eyewitnesses have told ITV News Central a number of loud explosions could be heard from the fire at G&P batteries in Darlaston, Walsall.
50 firefighters are currently tackling the blaze on Willenhall Road.
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East Midlands weather: Sunny spells but cloudy with rain at times later.
West Midlands weather: Some rain today, but showers clearing.
Police are appealing for witnesses after an elderly woman was attacked in her own home on Thursday.