The Los Angeles Police Department confirmed on Thursday night that it is investigating the Kenneth fire, one of the five wildfires ravaging the county, as a case of arson.
The police added that they have one suspect in custody.
The death toll of the fires is now estimated to be ten, and according to reports the two largest fires in the county have destroyed at least 10,000 structures, including homes and businesses.
Among the buildings destroyed by the fires was the Pasadena Jewish Temple and Center, with local media reporting that it burned to the ground within minutes.
The building that housed the Conservative Congregation was about 100 years old and dated back to the 1920s.
Earlier on Thursday, Israeli President Isaac Herzog expressed his condolences. "I am deeply saddened by the terrible wildfires in Los Angeles. From Israel, I send encouragement to all those affected, and my support to POTUS, Governor Gavin Newsom, the US government, and the state of California," Herzog wrote on X.
"We are following with concern and admiration the heroic efforts of the first responders, firefighters, policemen, paramedics, and volunteers who are risking their lives to save others. Our thoughts are with all those affected so terribly as well as with our Jewish sisters and brothers, mourning the loss of synagogues and institutions, while stepping up to help their communities and beyond," he added.