"Unified Command has reinstated the shelter in place order for a one-mile perimeter around the incident," the blog stated. "Unified Command advises anyone within the one-mile perimeter to turn off heaters and/or air conditioning systems that bring in outside air."
It noted that "gassing occurred" when crews attempted to remove the load from the vehicle.
Interstate 10 remains closed in both directions between Kolb and Rita roads, and Unified Command "anticipates an extensive closure." Unified Command is comprised of the Arizona Department of Public Safety, Tucson Police Department, and Tucson Fire Department.
A commercial truck tractor hauling a box trailer with liquid nitric acid rolled over on Interstate 10 eastbound between Rita and Kolb roads on Tuesday afternoon. Unified Command issued an evacuation order with a half-mile perimeter around the site and a shelter-in-place order with a one-mile perimeter before lifting the latter on Tuesday night. The driver was also confirmed dead.