JENIN, June 22 (IslamOnline & News Agencies) - Israeli occupation troops killed four Palestinians when they opened fire on a market in Jenin where people believed a curfew had been lifted Friday, June 21, amid a decision by Israeli Prime Minister Ariel Sharon's government to press ahead with its reoccupation of West Bank towns, news agencies reported.

In the West Bank city of Jenin, the scene of some of the heaviest fighting in the 21-month-old conflict, Palestinian medical sources said four people, all but one of them children, were killed on Friday afternoon when Israeli tanks shelled the fruit and vegetable market, reported Agence France-Presse (AFP).

A six-year-old girl and a 50-year-old man were the first to be struck down by the tank shells, they said.

Minutes later, a six-year-old boy and his 12-year-old brother were killed when a shell burst in the same area, they said, adding that about two dozen people were wounded in the firing.

The Israeli army said its tanks had ‘wrongly’ opened fire, causing the deaths and ‘vowed an investigation’, according to AFP.

It said in a statement that its tank fire on a group of people who "broke the curfew" in the city, where soldiers were carrying out "house to house searches in search of an explosives lab."

"An initial inquiry indicates that the force erred in its action," it said, but added it believed it had killed only three Palestinians.

"People thought the curfew was no longer on," Jenin's acting governor, Haider Irsheid, told the Israeli daily Ha’aretz.

"They got hungry and wanted bread, so they went to the market to buy some. The Israelis opened fire."

Before dawn, a 13-year-old Palestinian boy was also killed in Jenin and five members of his family wounded when Israeli soldiers blew up a house close to their own, a Palestinian hospital source said.

Violence also raged elsewhere in the occupied territories.

In another development, U.S. President George W. Bush Friday backed Israel’s ‘retaliation’ for a series of Palestinian attacks he called "outrageous," saying the U.S. ally has "the right to defend herself."

Meanwhile, a senior U.S. official said disagreements remained among top Bush aides over the details of a new Middle East peace plan he was meant to unveil in an eagerly awaited -- but as yet unscheduled -- speech.

"I wouldn't describe it as hot and heavy, but there is a robust exchange going on within the administration," said the official, who requested anonymity.

"I'll give the speech when I'm ready," said Bush, who was expected to push for a Palestinian state with temporary borders coupled with sweeping Palestinian political and security reforms meant to enhance Israel's security.

"All parties who are interested in getting on the path to peace must do everything they can to reject this terror. It is outrageous and it's got to be stopped," he said during a day-long visit here.

"I strongly condemn this series of attacks. I fully recognize that Israel's got the right to defend herself. The world must do everything in its power to prevent the few from creating misery for the many."

In Washington, State Department spokesman Richard Boucher said the United States was "deeply troubled" by the upsurge in violence, including shootings in Jenin and Gaza in which nine people were killed, said AFP.

"We would expect the Israelis to look into this kind of tragic incident," Boucher said.

Meanwhile, the U.S. State Department welcomed Palestinian leader Yasser Arafat's "positive" comments about making peace with Israel, referring to comments he made to an Israeli daily in which he pleaded for "no more war."

The United States on Friday questioned the need for a planned trip to the Middle East next week by a U.N. committee to investigate Israeli treatment of Palestinians in the occupied territories.

The State Department noted that Washington has been skeptical of the U.N. General Assembly's "Special Committee to Investigate Israeli Practices affecting the Human Rights of the Palestinian People and other Arabs of the Occupied Territories" since it was created in 1968 and has repeatedly voted to disband it.

"The United States has questioned whether this committee ... represents a wise use of U.N. funds," the department said in a statement.

"We have regularly voted against its continuation because we doubt its ability to make a meaningful contribution," it said. "Our doubts continue, and we question the need for this trip."