GAZA CITY, Gaza Strip - Hamas battled to wrest control of the Gaza Strip on Wednesday from beleaguered Fatah forces in the latest and most brutal round of violence. Each side's supporters have hurled rivals from high-rise buildings, gunmen have roamed hospital wards looking to finish off wounded enemies and ordinary people have huddled at home, not daring to walk the streets.

Q. Why are Palestinians fighting each other in the Gaza Strip?

A. After the Fatah movement of moderate Palestinian President Mahmoud Abbas was trounced in general elections by the militant Hamas movement last year, Abbas kept the main security forces under direct presidential control, prompting the Hamas-led government to put its own armed supporters on the streets. The spiralling power struggle between the two groups, fuelled by clan rivalries in the tightly knit coastal strip, have since erupted in waves of bloodshed.

Q. How many people have died in the fighting?

A. Since May last year, more than 260 Palestinians have died in factional fighting, at least 150 in the past month. Most of the casualties were armed members of the rival forces, but many bystanders have also been killed.

Q. What are the relative strengths of the two sides?

A. Hamas and Fatah fighters appear about evenly matched in the Gaza Strip, and fought to a draw in previous exchanges over the past year. Hamas, which commands roughly 20,000 armed men, has more firepower and better organization, while Fatah has more personnel, though an exact count is difficult.

Q.What is Israel doing and what are its options?

A. Israel does not want to be seen to be involved. Given that most Palestinians regard Israel as the enemy, it seeks to avoid an overt role. It has, however, discreetly been facilitating a resupply of arms and ammunition to Abbas' forces. Israeli Prime Minister Ehud Olmert favours deployment of a multinational force along Gaza's border with Egypt to prevent arms from reaching the militants.

A Hamas victory in Gaza, however, could force Israel's hand. Already, Hamas has fired hundreds of rockets at Israeli border towns, and a Hamas-controlled Gaza would likely give the rocket squads there freer rein. Israel could be forced to retaliate harshly to protect its civilians.

More dramatic steps, such as cutting off water and electricity supplies to Gaza, which has a densely packed population of 1.3 million, would create an uproar in the international community. Israeli hardliners are calling for a reoccupation of the entire territory, which troops and settlers left in 2005.