The reward for information that will lead to the arrests of the arsonists who sparked a deadly California wildfire this week has increased to $500,000.

Governor Arnold Schwarzenegger added $100,000 of state money to the reward on Friday.  More contributions came from a group of Native Americans, local officials and a local resident. 

Four firefighters with the U.S. Forest Service were killed Thursday when they were suddenly overtaken by a wall of fire as the winds shifted.  A fifth firefighter is hospitalized on life support with burns over 95 percent of his body.

More than 2,000 firefighters have been dispatched to battle the blaze, which had burned more than 16,000 hectares by nightfall on Friday. 

Authorities say the fire is at least 25 percent contained.  At least 10 homes have been destroyed.

The fire broke out Thursday morning in an area northwest of the resort town of Palm Springs.  Several hundred people were forced to evacuate their homes. 

Some information for this report was provided by AP and Reuters.