The Black Dragon Fire, also known as the 1987 Daxing'anling wildfire, was China's deadliest forest fire in history. It began in Heilongjiang's Daxing'anling Prefecture on May 6, 1987, and eventually spread into the Soviet Union. The fire is said to have started when a worker refueling a brush cutter accidentally ignited gas. It burned through three million acres of forest in Northeast China before crossing the Black Dragon River and burning an additional 15 million acres in the Soviet Union.