Israeli forces are maintaining the siege of a Palestinian Authority building in the West Bank city of Hebron. Israel says it is trying to capture 15 Palestinians militants.

Israeli tanks and helicopter gunships pounded the building, a former British police station, in an attempt to take the men holed up inside. The Israelis have fired thousands of rounds into building in a standoff that has been going on for three days.

Four Palestinians were killed the first day of the standoff.

More than 130 Palestinians have left the building and at least 20 have been taken into custody as terror suspects. The Israeli military said more than 100 explosive devices had been found in the area.

The standoff in Hebron is one of the few instances of violent resistance to Israel's new major military operations in the West Bank. Seven of the eight major Palestinian population centers are under almost round-the-clock curfew as part of an Israeli campaign to curb suicide bombings.

There was violence elsewhere in the West Bank, however. A six-year-old Palestinian boy was killed when an Israeli soldier opened fire on a group of youths throwing stones at tanks that were enforcing the curfew. Palestinian officials said a 12-year-old boy was also shot in the legs in the same incident.

Meanwhile, in Jericho, the only West Bank city without a major Israeli military presence, Palestinian officials released a plan for reform and elections. Just three days ago, President Bush demanded a new Palestinian leadership. He did not mention Yasser Arafat by name, but his statement left no doubt that the Palestinian leader must go.

The Palestinian plan called for presidential elections in January as well as an overhaul of the Palestinian Authority's courts and finances and a restructuring of security forces under a single command.

In announcing the plan, Saeb Erekat, a cabinet minister and the chief Palestinian negotiator, said Israel could make or break the election. He said it would not be possible to conduct the vote while Palestinian Authority areas were under Israeli control. "Elections cannot be carried out with tanks in every street," he said.

There were also conflicting reports about whether Mr. Arafat would be a candidate in January. Nabil Shaath, the authority's planning minister, said that Mr. Arafat would absolutely run again. But other officials, said it was too early to speculate on Mr. Arafat's plans.

The current Israeli military offensive came after two suicide bombings in Jerusalem killed 26 people last week.