Chinese police arrested four people on charges of starting China's worst fire, a blaze that killed more than 200 people and ravaged 2.5 million acres in a 20-day march across northeastern forests. Forestry Ministry officials said the flames, now extinguished, were sparked in two areas by brush-cutting machinery operated in violation of regulations. In two other areas, the smoldering cigarettes of temporary workers started fires. The flames, beginning May 6, grew into one giant fire in Heilongjiang province. Officials did not detail the charges against the four people arrested.