Pakistani forces fired at a fuel tank inside a controversial mosque early Saturday, causing an explosion heard across the capital, intelligence sources said. The fuel tank had been used for running generators in the besieged mosque, the sources said. There were no immediate reports of casualties. Shortly after the blast, gunfire erupted again between the radical Islamic students inside the Lal Masjid, or Red Mosque, and the Pakistani security forces outside. The four-day siege has resulted in at least 26 deaths. The latest confirmed deaths were two students who tried to surrender Friday but were shot dead by other students,...