EREZ CROSSING, Gaza Strip (AP) -- A female Palestinian suicide bomber blew herself up Wednesday at the major crossing point between Israel and the Gaza Strip, killing at least four Israelis and wounding seven other people, Israeli rescue services and media said.

The bomber set off the explosion in the area where thousands of Palestinian laborers and foreigners pass between Israel and the coastal strip, Israeli officials said. Four of the wounded were Palestinians, the army said.

Hamas and the Al Aqsa Martyrs' Brigades, linked to Palestinian leader Yasser Arafat's Fatah movement, issued a joint claim of responsibility.

They identified the bomber as Reem Raiyshi, a 21-year-old Hamas militant. She apparently is the first female suicide bomber from the militant Islamic fundamentalist group.

Hamas spiritual leader Sheik Ahmed Yassin said the use of a woman bomber was unique, but added that holy war "is an obligation of all Muslims, men and women."

The explosion occurred shortly before 10 a.m. The bomber, who had a metal plate in her leg, was ushered into an office where soldiers search people who have medical implants that trigger metal detectors, said Col. Pinchas Zuaretz, commander of Israeli forces in the southern Gaza Strip.

A Palestinian woman who identified herself only as Amena said she was waiting to get her permit renewed at the Erez crossing when four other Palestinian women entered an office ahead of her and the bomb went off.

"I heard soldiers screaming. The blast was very strong and I saw one of the women, the last one who went into the room, was bleeding from her legs," she said.

Another witness, who declined to be named, said an unfamiliar woman waiting with the laborers was walking strangely. When the witness offered to help the stranger, the woman brushed her off and the bomb went off shortly afterward.

The soldiers then forced everyone out and shut down the crossing, witnesses said.

The blast killed four people plus the bomber and wounded seven others, who were being evacuated to hospitals, said Moshe Vaaknin, an official with the Magen David Adom rescue services.

The Gaza Strip is surrounded by an Israeli security barrier. In the past three years of fighting, only one of the more than 100 suicide bombers has infiltrated Israel from the Gaza Strip.

But there have been several attacks at the Erez crossing.

"The Erez crossing is intended to better the lives of Palestinians to allow them to work in Israel. It just goes to show that Palestinian terrorists are more bent on attacking Israelis than bettering the lives of their own people," said David Baker, an official in the Israeli Prime Minister's Office.

The suicide bombing came on the heels of a West Bank ambush late Tuesday in which Palestinian gunmen killed a Jewish settler in a car at the entrance to the Talmon settlement near the West Bank city of Ramallah. The 28-year-old victim was the father of five, including triplets born two months ago.

The Al-Aqsa Martyrs' Brigades claimed responsibility.

Earlier Tuesday, Israeli troops killed a Palestinian gunmen in a firefight along the Gaza-Egypt border, the army said. The army said the soldiers were returning fire.

Meanwhile, an Israeli soldier was charged for the April shooting of Tom Hurndall, a British member of the International Solidarity Movement who was demonstrating against Israeli military operations in the Gaza Strip.

A military official, speaking on condition of anonymity, said the indictment could be upgraded to manslaughter because Hurndall died overnight in a London hospital, where he has been on life support for nine months.

The raging violence is one of the main causes of a serious economic crisis in the Palestinian Authority, which was forced to borrow from banks to pay the salaries of its 125,000 employees. The authority may not be able to pay salaries in February at all, Economy Minister Maher al-Masri told The Associated Press.

The seemingly endless fighting has made international donors -- one of the main contributors to the Palestinian budget -- wary about funneling more funds into the ailing Palestinian economy.

Tough Israeli travel restrictions also have damaged the economy.

Before fighting erupted, more than 100,000 Palestinians worked in Israel. Today, Israel grants permits to just a few thousand. The unemployment and the lack of international funding could trigger an unprecedented economic collapse.

The Palestinian Authority has a monthly income of about $20 million and expenditures of at least $85 million, al-Masri said. The Palestinians expect a deficit of at least $400 million, but the World Bank says donors have grown weary at the lack of progress toward peace.

Arab declarations of support for the Palestinians were not being matched by remittances, as only Saudi Arabia and Libya agreed to send money, al-Masri said.