Hundreds of firefighters battled a 100-acre blaze near the Snow Summit resort in Big Bear as darkness fell Sunday. Evacuations were ordered, and hundreds of homes were threatened by what is being called the Summit fire. Containment of the blaze was reported at 50 percent today as plane after plane and helicopter after helicopter dropped retardant and water from the lake on the blaze. Snow Summit’s snow making machines were shooting water in an attempt to help firefighters. Mandatory evacuations were called for in the areas from Knickerbocker Road east to Georgia Road, and south of Pennsylvania Road to the forest boundary, fire officials said. Voluntary evacuations were also in place for the area south of Brownie Lane, east of Thrush Drive, north of Switzerland Drive, and west of Summit Boulevard.