The fighting occurred near the Bureij and Nusseirat refugee camps in central Gaza after the security personnel began demonstrating to demand salaries on the eve of a major Muslim holiday. Battered by international sanctions, the Hamas-led Palestinian Authority has been largely unable to pay salaries to government workers since taking office in March.

Hamas militia members tried to quell the protest by the security men, who support the rival Fatah movement, witnesses said. A Hamas member was stabbed and moderately wounded, sparking several hours of gunbattles.

After a brief lull, the fighting resumed early Sunday, and Mohammed Shahadeh, a well-known Fatah activist, was fatally shot outside his home, hospital officials said. Three other people, including one bystander, were wounded. The fighting was continuing throughout the night, with gunmen from the rival sides posted on rooftops.

Tensions have been high since Hamas defeated the long-ruling Fatah in parliamentary elections this year. The tensions have spilled over into violence in recent weeks, killing nearly 20 people in Palestinian internal