Residents had little warning as a deadly blaze exploded overnight in Northern California -- leaping across the Sacramento River and hitting subdivisions in the city of Redding, south of the Oregon border.

"They say it was like a 'fire tornado,'" said Chris Corona, who lives in the area where the fire was burning. "People started driving on the curbs, through lawns, everyone was running."

"Fire tornadoes" are a real phenomenon. Intense fires can whip up towering spirals.

"You've got a lot of heat being generated right now around this Carr Fire and it's all from the fire itself, but there's a second source," said Lonnie Quinn, chief weathercaster for CBS New York.

The ambient air temperature in the area was close to 110 degrees, "so that air is super fast rising into the atmosphere," Quinn said.

"You need to think of this as the air being a solid, and if you're taking a chunk of that air, superheating it and rising into the air, it's leaving a void below it," he said.

As more and more air gets pulled in, it begins to rotate. The more air that gets pulled in, the faster the air swirls and the taller it gets.

"Firenados" also pick up burning embers, ash and flammable debris and extend hundreds or thousands of feet in the air. Those embers can then spread out, jumping fire lines and creating new fires away from the center.

A typical "firenado" is only a few feet wide and 100 feet tall but can easily grow up to 10 times that size and have winds up to 100 miles per hour.