'Orange-colored gas' plume fills air after truck accident spills hazardous chemicals in Arizona

TUCSON, Ariz. -- The Arizona Department of Public Safety is maintaining a shelter-in-place order to a one-mile perimeter around the hazardous spill of liquid nitric acid on Interstate 10 in Tucson.

The crash led to evacuation orders which were lifted Tuesday night, expanded to a three-mile radius Wednesday morning, and then reduced, authorities said.

"While crews were attempting to remove the load from the commercial vehicle, gassing occurred," DPS said in a news release.

"Recovery and mitigation efforts on the hazardous materials experienced temporary setbacks overnight due to weather conditions," officials said in an update.

"Crews have now removed the material from the truck and are utilizing dirt to mitigate further off gassing. Interstate 10 remains closed in both directions between Kolb and Rita roads in Tucson," the release added.

DPS did not indicate when the shelter-in-place would be lifted, according to CNN.

The Pima County Health Department and the Arizona Poison and Drug Information Center are offering guidance and urging residents who may have been exposed to the spill for at least 15 minutes to assess their exposure.

The driver of the truck died in the crash, the department said, without identifying the person publicly.

Shawn Bilkey said the orange-colored gas that came from an overturned tractor-trailer carrying liquid nitric acid smelled like smoke, "but not fire smoke ... just not pleasant."

Bilkey was driving east along I-10 Tuesday near the Rita Road exit, shortly after the truck overturned.

"The traffic never stopped while we were there, it had to have just happened because there was only one cop there at the time," he said.

He remembered traffic in front of him suddenly slowed, and then he began seeing the orange-colored gas in front of him.

"It was a color I'd never seen in vapor form before, so I decided to start recording," he said. "Just in case Tucson were to turn into East Palestine y'know?"

In the video, a thick plume of gas is seen emanating from the overturned tractor trailer. It's seen drifting northward, into and across the westbound Interstate 10 lanes.

"It didn't smell like anything when we drove by, probably helped that the wind was taking it in the opposite direction," Bilkey said. "But I was dropping off my friend who lives in Rita Ranch about half a mile north from where the spill was, in the direction the wind was blowing, and when he got out of the car it almost smelled like smoke but not fire smoke it's hard to explain, just not pleasant."

Nitric acid is a colorless liquid, has yellow or red fumes and acrid odor, according to the US Centers for Disease Control and Prevention. Exposure to it can cause irritation to the eyes, skin and mucous membranes.