Investigators are considering an array of possible ignition sources for the fires that have killed at least 10 people and destroyed thousands of structures in California.

Some residents in the Altadena neighbourhood have been returning to find their homes completely destroyed in the wildfires which ravaged the Los Angeles area this week.

The death toll from the worst wildfire in California history continued to rise, with the Los Angeles medical examiner reporting Thursday night that 10 people have died as a result of the blazes.

As wildfires continue to spread across southern California, experts are warning they could impact the mental health of residents and first responders.

Some returned to their homes to find nothing left after they were destroyed by the Los Angeles wildfires. NBC News' Gadi Schwartz met with some of them in the Altadena neighborhood.

Robert Gauthier has been with the Los Angeles Times since 1994. He was the photographer for a project detailing the failings of an L.A. public hospital that won the 2005 Pulitzer Prize for public service. Before The Times, Gauthier worked at the San Diego Union-Tribune, the Escondido Times-Advocate and the Bernardo News in San Diego County, his hometown. Mark E. Potts is the senior editor for video at the Los Angeles Times. A native of Enid, Okla., Potts graduated from the University of Oklahoma with a master’s degree in broadcast journalism. He has created and edited video for DreamWorks, YouTube, Microsoft, Sony and BET.