A natural-gas pipeline in Belgium, pierced by construction workers, exploded Friday in a huge pillar of flames that killed at least 15 people and injured more than 100, officials said. The blast crushed buildings, scorched cars and burned farm fields for hundreds of yards. Officials feared the death toll could rise because some of the injured were in very critical condition. The earthshaking blast occurred about 8:30 a.m. in an industrial area of the village of Ghislenghien, about 20 miles southwest of Brussels, the capital, and could be seen and heard for miles. Emergency crews from across Belgium and from France, Luxembourg and Germany rushed to help, and a gray haze hung over the rural area as helicopters and about 50 ambulances carried the injured to hospitals. U.S. troops who have a base nearby helped Belgian authorities, and France offered military medical teams. About a half-hour before the explosion, construction workers alerted firefighters that they had damaged the underground gas line, acting provincial Gov. Guy Petit said. At least five of the dead and many of the injured were believed to have been police officers and firefighters responding to the call. A towering wall of orange flames roared after the blast sent a series of huge fireballs boiling high into the sky. The shock wave crushed a swath of large buildings in an industrial park and hurled bodies more than 100 yards. Everything within 400 yards of the crater ripped open by the blast was melted or incinerated. "There were bodies in parking lots, in fields," said a spokesman for the Brussels fire department.