LAKE VIEW TERRACE , California ( CNN ) -- A massive fire that has charred more than 147,000 acres in Southern California and destroyed dozens of homes north of Los Angeles was caused by arson , a U.S. Forest Service spokeswoman said Thursday . A wildfire burns close to blackened hills in the Angeles National Forest outside Los Angeles on Wednesday . A homicide investigation has been initiated by the Los Angeles County Sheriff 's Department into the deaths of two firefighters as a result of the Station fire , said spokeswoman Rita Wears . The firefighters died Sunday in a vehicle crash while trying to escape fast-moving flames . The fire was at 38 percent containment Thursday . It has been burning for more than a week . Fire officials said progress has been made , particularly on the west side of the fire , but the blaze was still producing hot spots , including one that forced the evacuation of 25 residents early Thursday . Families in 11 homes were awakened at about 4 a.m. and given three hours to leave their homes near the Dillon Divide community . The fire had scorched 147,418 acres as of Thursday . Residents have fled from 10,000 homes along the edge of the Angeles Forest since the fire began on August 26 . However , the majority of evacuees were allowed back into their homes by Wednesday . Watch as firefighters struggle to keep the blaze at bay » . `` We 're fighting for every foot of containment we can get on this fire , '' said U.S. Forest Service Fire Chief Mike Dietrich . He said firefighters have made progress controlling the northern and western parameters of the fire , but the priority is to keep the southeastern corner of the fire away from areas along Interstate 210 , including Pasadena , Arcadia and Sierra Madre . The blaze is headed toward the San Gabriel Wilderness Area of the Angeles forest . The San Gabriel represents the eastern edge of the fire , he said . Nearly all the fire was in forest land and the nearby foothill communities , including La Canada Flintridge , La Crescenta and Acton . `` This is a very complicated situation , and it continues to be complicated as it moves east , '' Dietrich said . The fire has destroyed 64 homes , three commercial properties and 49 outdoor structures since it began last week , authorities said . The state has spent about $ 27 million so far fighting the fire in the Angeles National Forest , Dietrich said . Firefighters expect to have the blaze fully contained by September 15 . Earlier , Gov . Arnold Schwarzenegger was asked about the cost of the firefighting , given the state 's precarious financial position . `` I 've made it clear that even though we have a budget crunch and we have an economic crisis and we just solved a $ 23 billion deficit , we will always have the money available to fight the fires because public safety is our No . 1 priority , '' Schwarzenegger responded . That budget gap covers two years . The governor said he insisted that the state budget he signed in July have a $ 500 million reserve for emergencies such as fires . California has had 5,000 blazes so far this year , he said . He said 21 firefighters have been injured battling the Station fire , in addition to the two killed Sunday . While temperatures remain high , the humidity level increased on Wednesday and Thursday -- a boon to the firefighting efforts . Firefighters could get another break if temperatures cool off on Friday , as expected . CNN 's Barbara Starr in Lake View Terrace , California , contributed to this report .
Investigation treated as homicide case because two firefighters died . The fire was at 38 percent containment Thursday , officials say . Station fire has burned more than 147,000 acres north of Los Angeles . Comment: