HOUSTON — Seven sheriff’s deputies and emergency medical responders who say they were sickened by a chemical fire at a plant outside Houston that flooded during Harvey sued the owner Thursday for gross negligence, seeking $1 million in damages.

A state judge granted a temporary restraining order to prevent plant owner Arkema from removing evidence or altering the scene, said Kimberly Spurlock, the attorney for the plaintiffs. She said a hearing was set for Sept. 22.

The suit alleges Arkema failed to properly store the estimated 18 tons of chemicals that burned or prepare for a major flood even though it was a foreseeable event.

Record rains from Harvey flooded the plant 25 miles northeast of Houston with six feet of water, according to a report Arkema filed with the state. The storm knocked out power, and therefore the refrigeration needed to keep the chemicals stable.

Spurlock called Arkema’s preparations “woefully inadequate” and questioned why the first responders did not know what chemicals were blowing up or the risks.

“They weren’t told to wear masks, They weren’t told to go in there with safety equipment and they’re suffering as a result,” Spurlock said.

Arkema said in a statement that it will “vigorously defend” the lawsuit.

The chemical compounds — organic peroxides used to make a gamut of products from plastics to paints — became unstable and exploded in flames more than 30 feet high early on Aug. 31, spewing an acrid plume of smoke.

The Harris County sheriff’s deputies who sued were manning the 1.5-mile perimeter of an evacuation zone set two days earlier after plant workers abandoned the facility, warning of impending disaster.

The suit says they doubled over vomiting, gasped for air and “began to fall ill in the middle of the road.”

No one from Arkema warned of toxic fumes, it says, and when medical personnel arrived to help they were overcome “even before exiting their vehicle.”