At first, Palestinian officials blamed Israeli tank fire, reports CBS News Correspondent Robert Berger, but later admitted that it was a so-called work accident. The dead Palestinians were members of the Al Aqsa Martyrs Brigade, a militia linked to Yasser Arafat's ruling Fatah faction.
Loudspeaker trucks later drove through the Beit Hanoun area saying that the four died while "fulfilling their national duty," a phrase used in the past to announce accidental deaths. Israeli military sources said on condition of anonymity that the militants were on their way to plant a bomb and it went off prematurely.
Secretary of State Colin Powell Monday said "a few individuals" are trying to "blow up" the road map to Middle East peace — and they can't be allowed to succeed.
At a news conference in Jordan, Powell was asked about the news that four Palestinian militants were killed when a bomb they were planting went off in northern Gaza.
He said there are those in Hamas and other militant groups "who do not want to see progress towards peace." Powell predicts the groups will continue to try to frustrate peace efforts through terrorist acts — but that such efforts must move forward.
Israel is defending its policy of targeted killings, saying the Hamas terrorist who was killed Saturday by Israeli commandos in the West Bank town of Hebron was responsible for suicide bombings that killed 52 Israelis.
"The targeting of innocent civilians deliberately, and that's what the terrorists of Hamas are doing, is a war crime. It's something that we cannot accept," said cabinet minister Benjamin Netanyahu.
Israeli officials say if American citizens were being massacred, the U.S. government would go after the terrorists.
Powell said Sunday the killing of a Hamas leader Abdullah Kawasme, 43, in Hebron by Israeli troops could impede fulfillment of the U.S.-backed "road map" to peace.
"We cannot allow ourselves to be stopped because of these incidents," he said.
Powell met with diplomats from the other three members of the Quartet of Mideast mediators — the European Union, United Nations and Russia — to try to rescue the plan.
After the meeting, the Quartet members, in a strongly worded statement, said they "deplore and condemn the brutal terror attacks against Israeli citizens carried out ... since the road map's presentation," including a suicide bombing in Jerusalem on June 11 that killed 17 and Friday's gunfire attack on a car in the West Bank, killing a dual U.S.-Israeli citizen.
The statement did not condemn Israel's extrajudicial killing of Palestinian militants, while criticizing "Israeli military actions that result in the killing of innocent Palestinian and other civilians."
While the "road map" plan does not specifically rule out "targeted killings," as the Israelis call the assassination of suspected Palestinian militants, it says Israel must refrain from "actions undermining trust."
Israel has claimed the right to take out "ticking bombs," which it defines as terrorists carrying explosives as well as leaders who recruit and send them on missions.
Meanwhile, Palestinian officials said Monday they expect a positive response from Hamas on a truce with Israel soon, perhaps even by the end of the day, and Egyptian diplomatic sources said an announcement would be made in Cairo.
Israel has said this time that it would accept a truce, but only as a brief precursor to a crackdown on Hamas by Palestinian security forces. However, Palestinian Prime Minister Mahmoud Abbas has said he will not use force against the militants, for fear of sparking a civil war.
A Palestinian source involved in the truce talks said Monday that a final draft of the cease-fire proposal has been sent to Khaled Mashal, a top Hamas leader in Damascus.
The draft does not specify the duration of the truce, and this will be left to Egyptian mediators to determine, the source said. The document states that the armed groups are willing to give Abbas a chance to reach an agreement with the Israelis, according to the source.
The truce agreement was drawn up by Marwan Barghouti, a jailed Palestinian uprising leader, in his Israeli prison cell, said the source. Barghouti has been in close touch with Mashal through intermediaries, while Egypt has supervised the negotiations.
Egyptian diplomatic sources said Mashal was heading to Cairo later Monday or Tuesday, and that he would be accompanied by Ramadan Shalah, leader of the smaller Islamic Jihad group.
Several Palestinian Authority officials expressed optimism.
"Hamas told us they would give us an answer on Monday so we expect an answer today, and we expect it to be a positive one," said Foreign Minister Nabil Shaath, adding that they also expected "to get assurances about Israel's obligations not to carry out any attacks hopefully today as well."
Two other top officials, Cabinet Minister Yasser Abed Rabbo and adviser Sufian Abu Zaideh, also said that the direction was positive.
The Palestinian source said Hamas would relay its response to Egypt within 48 hours, and that a formal announcement was expected by Thursday in Cairo. Egypt has been trying for several months to try to persuade the armed groups to halt attacks on Israelis.