By IAN FISHER and STEVEN ERLANGER
...

But this latest shelling, on top of the Beit Hanun operation, which Mr. Abbas and Mr. Haniya had already called a “massacre,” caused Mr. Haniya to request a pause in the talks for three days of mourning.

In June, a similar cycle followed another apparently errant Israeli shell that killed Palestinian civilians, including seven members of a single family, the Ghaliyas, who were enjoying a day at the beach. The Israelis said they were shelling areas where rocket teams had fired into Israel, and denied that the shell that killed the Ghaliyas was theirs.

But no Palestinian believed the Israeli denial, there was never any conclusive alternative explanation and the military wing of Hamas announced that it was ending the cease-fire against Israel. The Hamas government belatedly went along, and Hamas started firing rockets again toward Israel, instead of simply supplying them to others.

More important, the Hamas military wing took part in the capture of the Israeli soldier, Cpl. Gilad Shalit, later in June, setting off the political crisis that surrounded — and has outlasted — Israel’s summertime war against Hezbollah in Lebanon.

Only days before the Shalit capture, Mr. Abbas and Mr. Olmert met together informally in Petra, Jordan, and promised to have a formal meeting within two weeks, actually setting a date for June 28, to begin their relationship afresh. Mr. Olmert promised Mr. Abbas to release 600 prisoners then. But with the capture of Corporal Shalit, the Hamas government found itself unable to repudiate the actions of its own military wing, apparently directed from Syria by Mr. Meshal.

Hamas later said it would reinstate the truce with Israel, but it might now break it again, and more decisively, because its experiment in government appeared to be foundering.

“I don’t believe in the rockets, but their reactions cannot be justified,” Mr. Abbas said of the Israelis. “We totally condemn the international silence and any acts that can be used as justification for the Israeli massacres.”

Leaders at the United Nations and the European Union, and in Russia, Britain and Italy, did condemn the incident. “It is hard to see what this action was meant to achieve and how it can be justified,” said the British foreign secretary, Margaret Beckett.

Gordon Johndroe, a spokesman for the White House National Security Council, called for restraint by all parties, adding: “We deeply regret the injuries and loss of life in Gaza today. We have seen the Israeli government’s apology and hope their investigation will be completed quickly.”

A similar statement was issued in President Bush’s name.