At least 100 Palestinians were killed on Sunday in Israeli shelling of a Gaza neighborhood that left bodies strewn in the streets and thousands fleeing for shelter to a hospital packed with wounded, Palestinian witnesses and officials said.
The Israeli military said militants from Gaza's dominant Hamas group responded with anti-tank missiles and heavy weapon fire in some of the bloodiest fighting since Israel launched its Gaza offensive 13 days ago.
A two-hour "humanitarian ceasefire" in the area, agreed by both sides at the request of the International Committee of the Red Cross, broke down in minutes with each side blaming the other.
Palestinian President Mahmoud Abbas accused Israel of carrying out a massacre and declared three days of mourning.
The Israeli military said Hamas had fired rockets and built tunnels and command centers in Sheja and that it had warned locals to evacuate two days earlier. Its ground forces were backed up by air strikes and artillery, the army added.
Elderly men there said the Israeli attack was the fiercest they had seen since the 1967 Middle East war, when Israel captured Gaza.
Shifa hospital's director, Naser Tattar, said 17 children, 14 women and four elderly were among the 62 dead, and about 400 people were wounded in the Israeli assault.
Gaza's Health Ministry officials said at least 403 Palestinians, many of them civilians, have been killed and about 2,600 wounded in the 13-day offensive, that Israel says it launched to halt mounting cross-border rocket fire by militants.
On Israel's side, two civilians have been killed by cross-border fire and five soldiers have died in fighting. More than 50 Israeli troops have been wounded, hospital officials said.
Thousands fled Shejaia, some by foot and others piling into the backs of trucks and sitting on the hoods of cars filled with families trying to get away. Several people rode out of the neighborhood of 100,000 in the shovel of a bulldozer.
Video given to Reuters by a local showed at least a dozen corpses, including three children, lying in rubble-filled streets, though the footage could not be verified independently.
As the tank shells began to land, Shejaia residents called radio stations pleading for evacuation. An air strike on the Shejaia home of Khalil al-Hayya, a senior Hamas official, killed his son, daughter-in-law and two grandchildren, hospital officials said.
Israel, which has accused Hamas of using civilians as human shields by launching rockets from residential areas, sent ground forces into the Gaza Strip on Thursday after 10 days of air, naval and artillery barrages failed to stop the salvoes.
The military said it beefed up its presence on Sunday, with a focus on destroying missile stockpiles and a vast tunnel system Hamas built along the frontier with Israel.
"The operation is necessary and, if needed, we will broaden it," he told reporters while visiting wounded Israeli soldiers in a hospital in the southern city of Beersheba.
Egypt, Qatar, France and the United Nations, among others, have all been pushing for a permanent ceasefire, with little sign of progress.
Militants kept up their rocket fire on Israel on Sunday. Sirens sounded in southern Israeli towns and in the Tel Aviv metropolitan area. There were no reports of casualties on the Israeli side.
Israeli Prime Minister Benjamin Netanyahu said on Sunday that Israel will take "whatever action is necessary" to halt Hamas cross-border rocket attacks from Gaza and restore calm but insisted his forces were doing their utmost to avoid civilian casualties there.
"We try to target military targets and unfortunately there are civilian casualties which we regret and we don't seek," Netanyahu told CNN shortly after an Israeli attack on a Gaza neighborhood killed at least 62 Palestinians.
He accused Hamas of deliberately targeting Israeli civilians and of using Gaza residents as "human shields." Asked how long it would take Israel to complete an operation it says is intended to destroy Hamas weapons tunnels, Netanyahu said it was being done "fairly quickly," but gave no time frame.
Asked whether Israel intends to reoccupy the Gaza Strip, he said: "Nobody wants to go to excessive military lengths."
For his part, US Secretary of State John Kerry said the United States believes Israel has a right to defend itself from rockets fired from Gaza and from attacks launched from cross-border tunnels.
Kerry called on Hamas to consider a ceasefire. "It is important for Hamas to now step up and be reasonable and understand that (if) you accept the ceasefire, you save lives," he said.
In a separate interview on CNN, Kerry said President Barack Obama will ask him to go to the Middle East soon to aid in efforts to secure a ceasefire.
US President Barack Obama told Israeli Prime Minister Benjamin Netanyahu on Sunday that he has serious concerns about the rising number of casualties from clashes between Israel and the Palestinians.
Obama spoke by telephone to Netanyahu for the second time in three days. He told him Israel has the right to defend itself and he reiterated US condemnation of attacks by Hamas against Israel.
"The president also raised serious concern about the growing number of casualties, including increasing Palestinian civilian deaths in Gaza and the loss of Israeli soldiers," the White House said in a statement describing the conversation.
Obama told Netanyahu that US Secretary of State John Kerry will travel to Cairo soon to seek an immediate cessation of hostilities based on a return to a November 2012 ceasefire agreement.
"The president underscored that the United States will work closely with Israel and regional partners on implementing an immediate ceasefire, and stressed the need to protect civilians - in Gaza and in Israel," the statement said.
The Arab League described Israeli attacks on Gaza that have killed at least 60 Palestinians on Sunday as a "war crime".
Nabil el-Araby, the head of the Cairo-based Arab League, considers Israeli shelling and ground attacks in Shejaia in northeast Gaza a "war crime" against Palestinian civilians which Israel is responsible for, according to statement issued on Sunday.
In turn, the Qatari foreign minister condemned the deaths of dozens of Palestinians in the Gaza Strip on Sunday as a "massacre" and called for a ceasefire that would ensure the lifting of a blockade on the coastal region.
UN Secretary-General Ban Ki-Moon, speaking at a joint news conference with the minister, Khaled al-Attiya, described Israeli-Palestinian fighting in Gaza as an "open wound and we must stop the bleeding now".
Western-backed Abbas in April struck a reconciliation deal with Hamas, which seized the Gaza Strip in 2007 from forces loyal to his Fatah movement. The agreement led to the formation of a Palestinian unity government and Israel's pullout from US-brokered peace talks.
Hamas has already rejected one Egyptian-brokered truce, saying any deal must include an end to a blockade of the coastal area and a recommitment to a ceasefire reached after an eight-day war in Gaza in 2012.
Hostilities escalated following the killing last month of three Jewish students that Israel blames on Hamas. Hamas neither confirmed nor denied involvement.
The apparent revenge murder of a Palestinian youth in Jerusalem, for which Israel has charged three Israelis, further fuelled tension.
REUTERS
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