"It's believed that because it's been relatively calm, many of these children went outside to enjoy themselves on this Eid holiday but tragically they've been killed," Tyab said.
Children killed in Gaza playground shelling
Israel denies hitting Gaza's main hospital and a playground, where seven children were killed.
Last updated: 28 Jul 2014 18:03
Eight people including seven children died following a missile strike on a park inside the Shati refugee camp [AFP]
Missiles have struck several sites in Gaza, including a park inside a refugee camp and an outpatient building of the strip's largest hospital, disrupting a relative lull at the start of the Muslim Eid al-Fitr holiday.
Eight people, including seven children, died following missile fire on a park inside the Shati refugee camp on the edge of Gaza City, medics said.
The children were playing on a swing when the strike hit the park, Ayman Sahabani, the head of the emergency room at Shifa hospital, told reporters.
The Israeli army swiftly denied it was behind the strike, tweeting that a misfired rocket from Gaza had hit the playground.
"We had no activity in the area. We know it was launched from within Gaza and landed short," Lieutenant Colonel Peter Lerner, an Israeli army spokesman, said.
However Hamas denied it had fired any rockets in the area and said it was "categorically an airstrike by Israel". It said it had collected schrapnel from the scene that it could prove was from an Israeli munition.
Medics said that an Israeli missile also hit a building, believed to be an outpatient clinic, close to the main gate of Shifa hospital, the same hospital where the victims of the playground strike were taken.
Al Jazeera's Imtiaz Tyab, reporting from the hospital, said there were chaotic scenes as "a number of small bodies were brought into this hospital".
"It's believed that because it's been relatively calm, many of these children went outside to enjoy themselves on this Eid holiday but tragically they've been killed," Tyab said.
Israelis killed
Also on Monday, four Israelis were killed in a mortar attack at Eshkol in southern Israel near the Gaza border.
The Israeli army hasn't commented on whether the four were soldiers or civilians, but the army has been deployed heavily in that area.
Monday’s violence followed an almost 12-hour pause in fighting and came as international efforts intensified to end the three-week war between Israel and Hamas.
The United Nations on Monday called for an "immediate" ceasefire in the fighting that has already killed more than 1,040 Palestinians, 43 Israeli soldiers and three civilians on the Israeli side.
At least two more Palestinians were killed in other attacks on Monday. A four-year-old boy died when tank shells hit his family's house in Jabaliya, in the northern Gaza Strip, Gaza health officials said. Another person was killed by tank shelling in a separate incident, also in Jabaliya.
The military said at least a dozen rockets had been fired from Gaza at Israel since midnight.
Eid of mourning
As Muslims began celebrating Eid al-Fitr, there was fear and mourning on Monday instead of holiday cheer in large parts of Gaza.
Palestinian families huddled inside their homes, fearing more airstrikes, while those who came to a cemetery in Gaza City's Sheik Radwan neighbourhood to pay traditional respects at their ancestors' graves gathered around a large crater from an airstrike a week ago that had broken up several graves.
Amid an eerie calm, the call to Eid prayer echoed in the southern town of Rafah on Monday morning. Dozens of worshippers lined the rows of a severely destroyed mosque, with a collapsed roof and missing walls. Many of the faithful looked sombre during the traditional holiday sermon.
In Gaza City, dozens of men prayed in the courtyard of a UN school surrounded by school desks. Children and women stood on a higher level overlooking the worshippers.
"We are suffering and will suffer but we need our rights, our houses, our lands and our farms to return to us and we will not accept living a miserable life," said Abu Saber Jalees, who fled fighting to seek shelter at the school.
Amid a slowdown in the fighting, rescue teams uncovered five bodies in a village east of Khan Younis, said Saed al-Saoudi, the commander of the Civil Defence in Gaza.
UN unsuccessful truce bid
In New York, an emergency meeting of the UN Security Council called for "an immediate and unconditional humanitarian ceasefire".
And while it was the council's strongest statement yet on the Gaza war, it was not a resolution and therefore not binding.
The council's presidential statement also called on the parties "to engage in efforts to achieve a durable and fully respected ceasefire, based on the Egyptian initiative."
Benjamin Netanyahu, the Israeli prime minister, spoke with UN chief Ban Ki-moon, according to a statement from his office, in which he voiced his dismay with the announcement.
"It does not include a response to Israel's security needs and the demilitarization of the Gaza Strip," he said.
Palestinian UN Ambassador Riyad Mansour also did not hide his disappointment.
He said the council should have adopted a strong and legally binding resolution a long time ago demanding an immediate halt to Israel's "aggression," providing the Palestinian people with protection and lifting the siege in the Gaza Strip so goods and people could move freely.
"You cannot keep 1.8 million Palestinian civilians in the Gaza Strip in this huge prison," Mansour told reporters. "That is a recipe for disaster. It is inhumane, and it has to be stopped and it has to be lifted."