Seven emergency workers who responded to the aftermath of last month's mega-storm Harvey sued chemical company Arkema Thursday for exposing them to smoke from a fire at its flooded Texas plant.

The $1 million lawsuit alleges negligence, claiming Arkema did not adequately prepare for potential flooding, forcing it to abandon the plant near Houston as waters rose without adequate safeguards to avoid volatile chemicals catching fire. 

The lawsuit also says Arkema downplayed the danger and did not immediately warn nearby first responders after the first of nine truck-sized containment trailers ignited last Thursday -- sending thick black smoke high into the sky. 

Arkema called the lawsuit "gravely mistaken," adding that it regretted any harm caused "as a result of the havoc wreaked on our plant by Hurricane Harvey."

"We reject any suggestion that we failed to warn of the danger of breathing the smoke from the fires at our site, or that we ever misled anyone," the company said in a statement.

Arkema insisted it did all it could amid five to seven feet (1.5 to 2.1 meters) of floodwaters, pointing to the 1.5-mile (2.4 kilometer) evacuation zone established around the plant as officials waited for the chemicals to burn out.

The company had deemed it too risky to move the chemicals as the storm was bearing down on the Houston area. Once its refrigeration systems and backups failed, the chemical compounds began to decompose and overheat.  

The lawsuit describes a dramatic scene after the initial fire and accompanying smoke.

"One by one, the police officers and first responders began to fall ill in the middle of the road," the complaint filed in Harris County court alleges. 

"The scene was nothing less than chaos. Police officers were doubled over vomiting, unable to breathe."

Fifteen sheriff's deputies were briefly hospitalized, according to authorities. 

At a news conference after the first fire, company executive Richard Rennard -- who is also named in the lawsuit -- held back from describing the smoke as toxic, instead saying it was "noxious" and an "irritant."

"Toxicity, it's a relative thing," Rennard said. 

On Sunday, the company decided to deliberately set ablaze the remaining trailers, because they had not yet fully burned.