A suicide bomber blew herself up at a bus stop in central Jerusalem Friday, killing six people and wounding at least 84 others at a crowded marketplace packed with shoppers just before the start of the Jewish Sabbath.

The Al Aqsa Martyrs Brigade, the militia linked to Palestinian leader Yasser Arafat, claimed responsibility for the blast.

Glass shards, twisted metal, blood and body parts were strewn across the asphalt at the  crowded Mahane Yehuda market, which has been the scene of several other recent bombings.

Israel Radio identified the bomber as Nidal Daraghmeh, a woman from the Jenin refugee camp in the West Bank that has been the scene of the deadliest fighting during Israel's 2-week-old military offensive in the West Bank.

A photographer said he saw the severed head of a woman at the scene.

Secretary of State Colin Powell was at a nearby helipad at the time of the attack, waiting to board a helicopter that would take him to Israel's tense border with Lebanon. Powell had met earlier in the day with Israeli Prime Minister Ariel Sharon in his effort to reach a peace accord between the Israelis and Palestinians.

Defense Minister Binyamin Ben-Eliezer  took Powell for a brief helicopter tour of the scene before he left the city. A State Department official said later that Powell had spoken to Sharon to express his regrets and was reconsidering his plan to meet with Arafat on Saturday.

The White House called on Arafat to make a public statement denouncing terror.

"Yasser Arafat needs to come out and publicly condemn today's attack," White House spokesman Ari Fleischer said. "This is terrorism. This is murder and Yasser Arafat needs to denounce it soon."

Sheikh Ahmad Yassin, spiritual leader of the militant group Hamas, said the bombing was punishment for Israel's military offensive.

"If Israel thinks that after what they did in Jenin and Nablus they will not be punished, they are mistaken," Yassin said. "This is part of the punishment. They should wait and see. More is coming."

The bomber set off her explosives shortly after 4 p.m., when shoppers hunt for pre-Sabbath bargains at the marketplace.

Moments later, a shopper who gave only her first name, Elisheva, frantically tore pieces of clothing to use as bandages. "I was holding a girl, who was gushing blood from her face," Elisheva said. "She said to me, 'Today is my 17th birthday. Why is this happening?' We were just holding each other and crying and crying."

Police Chief Mickey Levy said the bomber failed to reach the heart of the market or get onto a bus because of tight security, so "he exploded himself as he was trying to get on bus." Levy spoke before the bomber was identified as a woman.

A witness who gave only his first name, Shimon, said he was standing at the bus stop when the bomb went off. "The body of the terrorist fell on me and we were pushed into the Hava bakery," he told Israel Radio. "I couldn't move around because there were pieces of flesh and bodies around me."

Jerusalem's mayor, Ehud Olmert, who was in the market buying bread and left moments before the blast, denounced U.S. and international pressure on Israel to end its offensive as suicide blasts continue.

"It shocks me that there is an international effort, campaign, to prevent Israel from fighting terror and to make it bend to terror," Olmert said.

Friday's blast was the fifth suicide attack since Israel launched "Operation Defensive Shield" on March 29. Twenty-five Israelis have been killed in the five bombings.

David Baker, a spokesman for Sharon, called the blast "another murderous attack by Palestinian terrorists against innocent Israelis at the busiest time of the week in the busiest market in Jerusalem."

"It is clear that Arafat and the Palestinian Authority exist for one purpose, spreading terror," Baker said.

The Associated Press contributed to this report.