Around 100 residents and workers were evacuated after fire broke out in a waste plant sparking a chemical alert.
The blaze in a number of large oil drums caused plumes of black smoke visible from miles around as it spread through Arrow Environmental Services in West Bromwich.
Acrid smoke shot into the air from the fire, which started at around 1.45pm in part of the premises used to recycle waste oil.
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Staff at the firm in Kelvin Way faced a huge clean-up today as oil had flooded from the building onto land outside. The cause is not yet known but it is suspected the hot weather may be to blame. Workers at the scene described how the flames escalated in seconds and a series of bangs followed.
Around 35 firefighters tackled the blaze at its height and hazardous materials officers were drafted in. Firefighter Steve Husbands said crews faced a fight to stop the waste oil entering water courses. Also an oxygen cylinder exploded, causing a fireball, and about seven other cylinders had to be removed amid fears they would also blow up.
Arrow declined to comment.