There has been an apparent attempt to assassinate a top Palestinian security official loyal to President Mahmoud Abbas.
Intelligence chief Tareq abu Rajab is reported to be among half a dozen officials wounded in a bomb blast at the Gaza headquarters of the security forces. One bodyguard is said to have been killed.
The blast came after a night of armed clashes between gunmen from the rival Hamas and Fatah factions
The new Hamas militia has been expanding its deployment in the Palestinian territories, taking up positions for the first time in the southern Gaza Strip.