Israeli air strikes in the Gaza Strip killed 10 people, medics say, on day 12 of a major operation against the Palestinian territory.
The first strike killed seven people, including three from the same family and a woman, outside a mosque in the southern city of Khan Yunis, emergency services spokesman Ashraf al-Qudra said.
Three more people were killed shortly afterwards, in three separate strikes in Beit Hanun in the north, Deir al-Balah in central Gaza and another in Khan Yunis.
The deaths took the toll from an Israeli operation to stamp out rocket fire from Gaza to 306, many of them women and children.
One Israeli civilian and one Israeli soldier have been killed since the campaign started on July 8. The soldier was killed by a tank shell in a friendly fire incident.
Israeli Prime Minister Benjamin Netanyahu said he had ordered the army to prepare for a possible expansion of an Israeli ground push into the Gaza Strip as more tanks and infantry streamed into the coastal enclave.
Israeli forces operating along the length of Gaza's border with Israel advanced up to 3km inside the territory, scouring the area for tunnel networks dug by the militant Islamist group Hamas, military officials said.
There were scattered firefights with militant gunmen, in which 17 were killed, the army said.
Despite the Israeli thrust, rocket launching from Gaza continued with fresh volleys fired at Tel Aviv.
There were no casualties as the incoming projectiles were intercepted by Israel's Iron Dome missile defence system.
Chris Gunness, spokesman for the United Nations Relief and Works Agency, which assists Palestinian refugees, said more than 47,000 people fleeing the fighting had taken refuge in 43 shelters run by the agency, most of them schools.
He said the overall number of displaced people in the Gaza Strip was likely far higher because many people had taken shelter with family and friends.
US President Barack Obama said he had spoken with Netanyahu, reaffirming his support for Israel's right to defend itself but also cautioning against a broadening of military operations in a way that would increase civilian casualties.
A convoy of Israeli armoured personnel carriers (APC) move towards the Israeli-Gaza border. Photo / AFP
"Although we support military efforts by the Israelis to make sure that rockets are not fired into their territory," Obama said, "we also have said that our understanding is the current military ground operations are designed to deal with the tunnels, and we are hopeful that Israel will continue to approach this process in a way that minimises civilian casualties."
In televised remarks before the weekly meeting of his Cabinet, Netanyahu said he had instructed the army "to be prepared for the possibility of a significant expansion of ground operations".
He said the ground offensive was meant to "hit terror tunnels that penetrate from the Gaza Strip to Israeli territory".
On Thursday the army said it had foiled an infiltration attempt by more than a dozen heavily armed Hamas militants through a cross-border tunnel.
Military officials said forces operating in Gaza had uncovered at least 10 tunnels that were part of an extensive underground network that connected command centres with rocket-launching sites, and in some cases crossed the border to Israel.
Efforts to broker a ceasefire are continuing with Palestinian Authority President Mahmoud Abbas meeting Turkish leaders.
He was scheduled to continue on to Qatar for further discussions.