LOS ANGELES - An estimated 800 firefighters were clearing new fire lines and holding existing ones in hopes of containing the Williams Fire that has burned more than 4,000 acres in the San Gabriel Canyon in the Angeles National Forest, according to a U.S. Forest Service update. After two days of clearing an area of brush to contain the fire, it was still around only five percent of the fire, officials said. They expected to have a line around the entire fire that is burning in medium to heavy chaparral and mixed conifers by Thursday, September 13th. It was moving to the north- northeast in an area that has not burned in 15 to 20 years, authorities said. The acreage was revised downward from 4,000 acres due to more accurate mapping. The air attack was expected to continue, with 11 air tankers and 10 helicopters, officials said. A DC-10 tanker made two drops Sunday. Firefighters also planned to protect structures in the Camp Williams area, officials said. Camp Williams and the San Gabriel Canyon were ordered evacuated, but 25 people decided to stay anyway. The fire began about 2:15 p.m. Sunday in the Camp Williams trailer park, along East Fork Road off of San Gabriel Canyon (39) Road, L'Tanga Watson of the U.S. Forest Service said. There was a search Monday for three hikers who were reported stranded in the San Gabriel Canyon near the Williams Fire, a county fire department supervisor said. ``We sent out a search and rescue helicopter and searched the area they were reportedly in but we found nothing,'' county fire Dispatch Supervisor Art Marrujo said. ``So we called off the search at 2:38 p.m. and recalled the helicopter.'' The hikers were reported stranded in the east fork of the San Gabriel Canyon near the Bridge to Nowhere, a popular hiking destination on East Fork Road above Azusa, according to the county fire department.