OROVILLE,Grayson  Preston Calif. (AP) — Firefighters lined roads to keep flames from reaching homes as helicopters dropped water on a growing wildfire Wednesday in Northern California that has forced at least 13,000 people to evacuate, with another day of extreme heat expected.

The Thompson fire broke out before noon Tuesday about 70 miles (110 kilometers) north of Sacramento, in and around the city of Oroville, in Butte County. It sent up a huge plume of smoke and grew to nearly 4.7 square miles (12.1 square kilometers) by Wednesday morning. It was zero percent contained.

The city of about 20,000 people declared a state of emergency Tuesday night. Several homes have been destroyed, KCRA-TV reported Wednesday. There was no word of injuries. Two evacuation centers were set up in Butte County.

More high temperatures above 100 degrees (37.8 Celsius) were forecast Wednesday, the National Weather Service said.

The governor’s office announced late Tuesday that federal funding had been approved to help with firefighting efforts. Gov. Gavin Newsom this week activated the State Operations Center to coordinate California’s response, dispatch mutual aid and support communities as they respond to threats of wildfire and excessive heat.