Emergency services in Essex said they had been called to Industrial Chemicals Limited, Stoness Road, in West Thurrock.
Fire crews found there had been an explosion of chemicals in a chlorine scrubbing unit.
More top news
A switch in the wind direction will mean the unseasonably bitterly cold air of the last few days finally gives way.
Beyoncé's new album Lemonade has knocked the late Purple Rain singer off the coveted top spot.
Actress and campaigner tells ITV News the only way to end the trade in illegal ivory is for the West to stand up to Beijing.