Gaza crisis: Fresh fire exchanged as violence continues
The Israeli army and militants in Gaza are continuing to trade fire, with the round of violence that has followed Israel's killing of Hamas's military chief showing no sign of abating.
Israel hit 200 sites overnight, including PM Ismail Haniya's office.
Gaza militants fired dozens of rockets into Israel, including one at the city of Tel Aviv that was intercepted.
Egypt's president says there are "some indications" a truce could be reached but that there are "no guarantees".
Mohammed Mursi was speaking in Cairo after meeting Turkish Prime Minister Recep Tayyip Erdogan. Hamas leader Khaled Meshaal is also in the Egyptian capital for talks.
The Arab League has been holding an emergency meeting, also in Cairo, and announced it would send a delegation to Gaza in the next few days.
At least 40 Palestinians and three Israelis have now died since Israel killed the Hamas military chief Ahmed Jabari on Wednesday.
Early on Sunday morning, BBC correspondents in Gaza reported hearing heavy shelling, which they said appeared to be coming from the sea.
One missile reportedly hit a building used by Palestinian journalists in Gaza City.
The BBC's Rushdi Abualouf in Gaza tweeted: "At least 3 journalists have been injured in an Israeli air strike on building housing for local media."
Israel's military says there are still hundreds of sites it wants to target in the Gaza Strip.
A spokeswoman also told the BBC that troops gathered near the border were ready to invade should the Israeli government give the order.
She said Israel not see any distinction between the military and political wings of Hamas and that anything connected with the group was considered a legitimate target.
An Israeli air force spokesman said it had destroyed at least 90% of long-range rockets in Gaza and severely damaged medium- and short-range rockets, and the infrastructure to fire them. However, hundreds of short-range missiles remained, he said.
The BBC's Richard Galpin in Jerusalem says that despite the ferocity of the Israeli bombardment, some 60 rockets were reported to have been fired into Israel on Saturday, with some buildings damaged and four soldiers suffering minor injuries.
Sirens went off around Tel Aviv on Saturday. Israel's military said a missile had been intercepted by a newly installed battery of its Iron Dome defence system.
One rocket also hit an apartment building in the Israeli port city of Ashdod, wounding several people.
Israel has now put 75,000 reservists on stand-by, on top of the 16,000 called up in recent days.
Our correspondent says that, so far, there has been no decision on sending in the troops. However, one government minister has been quoted as saying that soldiers could launch a ground offensive into Gaza within the next 24 hours if the rocket fire does not stop.
The Israel Defense Forces (IDF) released figures on Saturday stating that over the past three days, 492 rockets fired from Gaza had hit Israel, while another 245 had been intercepted by Iron Dome.
On Saturday, Gaza City was hit by a string of large explosions shortly after 03:00 (01:00 GMT).
There was another series of strikes in and around the city after 05:00, with several hitting Hamas's cabinet buildings, which correspondents say were likely to have been empty.
The house of a Hamas leader in Jabaliya, north of Gaza City, was also hit.
Israel said it was targeting rocket launchers, weapons storage facilities and smuggling tunnels on the border with Egypt in southern Gaza.
Israeli military spokeswoman Avital Leibovich said 200 targets had been hit overnight.
Government spokesman Mark Regev told the BBC the operation would end when Israeli citizens were safe, and that all options - including a ground incursion - remained "on the table".
However, Interior Minister Eli Yishai was quoted by Israel's Haaretz newspaper as saying that the goal of the operation was "to send Gaza back to the Middle Ages. Only then will Israel be calm for 40 years".
Militants and civilians, including at least seven children, have been among the Palestinians killed during Israeli strikes in recent days, Hamas says.
The three Israelis who died were in a building in the southern town of Kiryat Malachi which was hit by a rocket on Thursday.
In Cairo, President Mursi said he had been in touch with both the Israelis and Palestinians.
"There are some indications that there is a possibility of a ceasefire soon, but we do not yet have firm guarantees," he said, after his meeting with Mr Erdogan.
Ahead of the meeting, Mr Erdogan said: "It's a tactic of Israel's to point the finger at Hamas and attack Gaza.
"Israel continues to make an international racket with its three dead. In fact it is Israel that violated the ceasefire."
Earlier, a senior Hamas source in Gaza told the BBC a proposal for a truce made by Turkey was being studied by the Hamas delegation in Cairo.
The Arab League said it had agreed to send a delegation to the Gaza Strip, headed by Secretary General Nabil el-Araby. He said it would take place in the next "one or two days".
In its statement, the League condemned Israeli "aggression" and expressed dissatisfaction at the UN Security Council's inability to bring about a ceasefire.