GAZA CITY, Gaza Strip - Fierce battles over strategic positions spread Wednesday to central Gaza, with Hamas fighters wresting control of the coastal strip's main north-south road and positioning to cut off reinforcements to beleaguered forces of the rival Fatah faction. In the southern town of Khan Younis, a one-ton bomb in an underground tunnel tore through the headquarters of a security force loyal to President Mahmoud Abbas of Fatah, said Ali Qaisi, a presidential guard spokesman. At least one person was killed and eight were wounded, medics said. Before the blast, Hamas militants demanded officers inside the building come...