McLean says three firefighters and an unknown number of civilians have burns but didn't know the extent.
The Carr Fire is "taking down everything in its path", he said.
Flames swept through the communities of Shasta and Keswick before jumping the Sacramento River and reaching Redding, a city of about 92,000 people and the largest in the region.
Residents of western Redding who hadn't been under evacuation orders were caught off guard and had to flee with little notice, causing miles-long traffic jams as flames turned the skies orange. All homes accessed from roads north of Hialeah were under mandatory evacuation, while homes south of Hialeah through just south of Highway 371, including those accessed from Hialeah, were under an evacuation warning, officials said.
William Blodgett of Idyllwild said he couldn't get home because of the fire and had to wait along with others at a gas station in nearby Mountain Center - until the fire hopped a highway and began to move in his direction.
The situation is "very dynamic" and "a heck of a fight", McLean added. No deaths have been reported.
The declarations issued Thursday state that hot temperatures, erratic wind and low humidity have increased the spread of both fires. In a matter of hours, the so-called Cranston Fire grew to 7.5 square miles (19 square kilometers). It is active again Thursday morning and has no doubt grown significantly since Wednesday. Crews had contained just 10 percent of it, according to the California Department of Forestry and Fire Protection.More news: Saudi Arabia suspends oil exports through Red Sea lane after Houthi attack
Whiskeytown was once a vibrant and bustling mining town.
The closure through at least Sunday led to at least 1,000 campground and hotel bookings being canceled, park spokesman Scott Gediman said.
The fire is one of several across California amid a heat wave that has seen days of triple-digit temperatures.
Cal Fire Law Enforcement Officers arrested Brandon McGlover, 32, of Temecula for allegedly setting multiple fires, including the Cranston Fire, in southwest Riverside County on Wednesday, according to a San Bernardino National Forest incident update. The state previously secured a fire management assistance grant from the Federal Emergency Management Agency to aid containment of the Carr Fire.
The fire in Shasta County was estimated at more than 31 square miles (80 square kilometers) Thursday morning.
Yet another wildfire has erupted in Riverside County's San Jacinto Mountains, this one near the community of Pinyon Pines.