Forest fires sometimes begin through natural events. Very little rainfall and dry forests are ideal situations for fires to start. All it takes is a lightning strike, sparking a fire that can destroy the entire forest. Often, forest fires are so large that firefighters can't stop them, and these fires sometimes threaten homes and businesses. Then, people are forced to flee the fire and hope that their property isn't destroyed.
Based on this passage, what is the initial cause of some forest fires?