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Emergency officials reported two blasts and black smoke issuing from the Arkema plant at Crosby.
During heavy rainfall from Hurricane Harvey, the complex lost the ability to refrigerate chemical compounds that need to be kept cool.
There was no way to prevent an explosion, the company had warned earlier.
Ahead of the explosions, one police officer who was helping secure the site was taken to hospital after inhaling fumes, while others admitted themselves to hospital as a precaution.
In a statement, the company said: "At approximately 2am CDT [07:00 GMT], we were notified by the Harris County Emergency Operations Center of two explosions and black smoke coming from the Arkema Inc plant in Crosby, Texas.
"Local officials had previously established an evacuation zone in an area 1.5 miles from our plant, based on their assessment of the situation.