Three big fires across Southern California this week already have burned through more than 100,000 acres, forcing tens of thousands of evacuations, destroying homes and leaving fire officials scrambling for resources. Governor Gavin Newsom traveled Wednesday to tour the Airport and Bridge fires, declaring states of emergency for Los Angeles, Riverside, and San Bernardino counties where the fires are burning. Newsom previously declared a state of emergency for the Line Fire, and he also toured a command center for that fire in Highland on Wednesday. Authorities say two of the fires, Airport and Line, were caused by humans, the first by accident and the other allegedly intentional. The cause of the Bridge fire is under investigation. All sparked in extremely hot and dry conditions. The cooler weather is helping firefighter efforts across the board, but all three fires still remain far from contained. All week, massive plumes of smoke have been visible throughout the region, prompting air quality warnings that are expected to continue.