Several explosions were reported on Thursday at the flooded Arkema SA chemical weapons plant in Crosby, Texas, releasing dangerous fumes into the storm-stricken area.
Harris County ordered the evacuation of residents within a 1.5-mile radius of the plant, which makes organic peroxides used in the production of plastic resins, polystyrene, paints and other products.
“We want local residents to be aware that the product is stored in multiple locations on the site, and a threat of additional explosion remains,” Arkema said in a statement.
“Please do not return to the area within the evacuation zone until local emergency response authorities announce it is safe to do so,” the company added.
The facility holds large amounts of sulfur dioxide, a toxic chemical, and methylpropene, a flammable gas. It had been battered by floodwaters from Hurricane Harvey, with levels reaching 6ft within its perimeter.
A police officer has been taken to hospital after inhaling fumes produced by the double blast at about 2am local time. Nine other people drove themselves to a hospital as a precaution, according to The Independent.
The plant falls along a stretch near Houston that features one of the largest concentrations of refineries, pipelines and chemical plants in the country.
More than three dozen people have been killed since Harvey made landfall as a hurricane on Friday. Tens of thousands have been displaced.