WEED, Calif. -- Hundreds of additional firefighters have been dispatched to a fast-growing wildfire in California as crews continue to mop up another blaze that tore through a small town.

More than 2,500 firefighters were battling the blaze near the town of Pollock Pines, about 60 miles (100 kilometres) east of the state capital, Sacramento, on Wednesday, up from about 1,500 the previous day. The fire grew by thousands of acres overnight and has burned through nearly 29 square miles (75 square kilometres).

It is threatening 500 homes, at least some of which are under mandatory evacuation orders, and is just 5 per cent contained.

Meanwhile, further north, crews are building and strengthening containment lines around a fire that tore through the town of Weed near the Oregon border on Monday. The blaze damaged or destroyed more than 150 structures, many of them homes.