International aid agencies have reacted with dismay to the violence in Gaza in which at least 18 Palestinian civilians are known to have died.
Unicef said it was distressed by the extraordinary violence
The Red Cross and Unicef said they were appalled by the deaths of women and children from Israeli tank fire in the town of Beit Hanoun.
Israeli PM Ehud Olmert has expressed regret over the attack and offered help for the many wounded.
Israel has ordered a halt to all artillery attacks in Gaza.
The Palestinian President, Mahmoud Abbas, said a massacre had been committed, and demanded intervention by the United Nations.
A senior figure in the Islamic militant group Hamas, Khalid Meshaal, called for retaliation.
The shelling has been condemned across Europe and the Middle East.
And a White House statement said US President George W Bush was "deeply saddened" by the injuries and loss of life.
It called for "appropriate steps" to be taken to avoid a repetition of the incident.
The International Committee of the Red Cross (ICRC) urged Israel to respect its obligations under international humanitarian law which prohibits attacks on civilians.
"Civilians must not pay the price of conflict," said Dominik Stillhart, the agency's head of delegation in Israel and the Palestinian territories.
"Any civilian loss of life further fuels the conflict and generates more loss, suffering and grief."
The UN children's agency Unicef said it was distressed by what it called the extraordinary violence in Gaza.
It said children there were living through a terrifying siege that would have an enduring impact.
Barrage of shells
John Dugard, the UN special investigator on human rights in the Palestinian territories, called on the Security Council to take action.
GAZA DEAD SINCE END OF JUNE
Total: 247 fatalities
155 civilian deaths
57 deaths of children
996 wounded, including 337 children (34%)
Source: Physicians for Human Rights (28 June to 27 Oct)
Mr Dugard, who is well known for his outspoken position on Gaza, said the quartet of the US, Russia, the EU and the UN, who are in charge of the roadmap peace plan in the Middle East, had done little to stop Israel's attacks, which he described as a brutal collective punishment of a people.
Palestinian officials said the incident was caused by a barrage of tank shells which hit civilian homes.
Thirteen of the dead were said to belong to the same family, and two of them were women and six were children.
Later on Wednesday, at least one Palestinian was killed in an Israeli air strike on Gaza City, Palestinian security and medical sources said.
Several others were reported to have been wounded in the missile strike.
The Israelis withdrew from the town on Tuesday following a major offensive centred in Beit Hanoun.
More than 60 Palestinians and an Israeli soldier were killed in a week-long operation that Israel says was aimed at stopping militant rocket fire into Israel from Gaza.
Three days of national mourning have been announced throughout the West Bank and Gaza Strip.