REDDING, Calif. (AP) An explosive wildfire that roared with little warning into a Northern California city claimed a second life and thousands more people abandoned their homes, some of them slipping out just ahead of the walls of flame, authorities said Friday.

In all, an estimated 37,000 people have fled from the so-called Carr Fire, which began Monday and tripled in size overnight Thursday amid scorching temperatures, low humidity and high winds. Fire officials warned that the blaze would probably burn deeper into urban areas before there was any hope of containing it.

A day earlier, the flames turned the sky orange while sweeping through the historic Gold Rush town of Shasta and nearby Keswick, then jumping the Sacramento River into Redding, a city of about 92,000 people and the largest in the region.