QALQILIYA, West Bank — Forces loyal to the moderate Palestinian president approached a Hamas hideout in the West Bank and set off a fierce gunbattle that left six dead Sunday, the worst violence since the factions fought a pitched battle over Gaza two years ago.
Militants lobbed grenades and fired automatic weapons to push back the raid on a two-story building in Qalqiliya, a West Bank town known for its strong Hamas presence. That drew dozens of President Mahmoud Abbas' forces to the hideout.
When it was over, pools of blood, tear gas canisters and hundreds of spent shell casings littered the floor. Walls were partly burned down during the battle.
Qalqiliya, which elected a Hamas mayor in 2005, was tense Sunday. Women gathered near the scene heaped insults on police officers. Sporadic gunfire erupted in other areas of town, and police said the shots came from Hamas loyalists targeting officers, though there were no reports of injuries.
The two factions have made intermittent attempts to reconcile since Hamas seized Gaza in 2007, leaving rival Fatah in control of only the West Bank. But Sunday's bloodshed showed just how little progress has been made.
The split has complicated Mideast peace efforts because the Palestinians cannot negotiate with Israel in a single voice and Hamas refuses to recognize the Jewish state.
Abbas has backed Washington's peace efforts, and the raid underscored his determination to rein in militants as part of his obligations under the U.S.-backed "road map" peace plan. Last week, Abbas met at the White House with President Barack Obama and renewed a pledge to crack down on militants and honor other commitments under the road map.
The United States has been training Abbas' elite forces to help him affirm his control of the West Bank and prepare for eventual statehood. Many of the security men involved in the shootout had undergone U.S.-supervised training in Jordan, police said.
Among those killed in the raid were two top Hamas militants who had been on the run from Israel for years. An unarmed Hamas supporter and three Palestinian police officers linked to Abbas' forces also died.
Tens of thousands of backers of Hamas and other militant groups marched in several places in Gaza City, protesting the raid and calling Abbas a collaborator with Israel. Abu Obeida, a spokesman for the Hamas military wing, threatened "tough and harsh reprisal."