A senior Israeli official arrived in Cairo Sunday morning for talks on reaching a cease-fire in the Israel-Gaza conflict, Egyptian officials told CBS News.

The officials said the official arrived at Cairo's airport and was immediately rushed away from the tarmac into talks.

The officials, speaking on condition of anonymity under security guidelines, did not identify the Israeli. Israeli officials declined comment.

Egypt has been leading international efforts to broker a truce to end five days of fighting between Israel and Hamas militants in Gaza.

Nabil Shaath, an aide to Palestinian President Mahmoud Abbas, who also was in Cairo, confirmed the Israeli's arrival and  said there are "serious attempts to reach a cease-fire." Shaath was headed to Gaza later Sunday to work on cease-fire efforts.

And Egyptian President Mohamed Morsi said late Saturday that there are indications an agreement to halt the fighting may be reached, Bloomberg reported. Turkish Prime Minister Recep Tayyip Erdogan, speaking before he departed for Egypt to meet with Morsi Saturday, said Hamas is ready to halt missile attacks if it is given guarantees by the U.S. that Israel also will stop firing.

But Israeli Prime Minister Benjamin Netanyahu continued to threaten an escalation of the attack.  

“We have extracted a heavy price from Hamas and other terrorist organizations, and the army is prepared to significantly widen the operation,” he said at the weekly Cabinet meeting today in Jerusalem. He said he spoke with U.S. President Barack Obama over the weekend and will continue talks with international leaders, according to an emailed statement from his office.

Meanwhile, Israel continued to bomb Palestinian militant targets in Gaza, including the media operations of Hamas, from the sea and air on the fifth day Sunday, news agencies reported.

Missiles hit two buildings used by both Hamas and foreign media in the center of Gaza City, injuring several Palestinian journalists, the Associated Press reported.

Militant rocket fire into Israel resumed Sunday morning after an overnight lull, with three rockets fired at the nearby coastal city of Ashkelon, Reuters reported, citing the Israeli military. Palestinian militants fired at least one more long-range rocket at Tel Aviv, the fourth day in a row which the Israeli heartland has come under fire.

Since the beginning of fighting 48 Palestinians, about half of them civilians, including 13 children, have been killed, Reuters reported, citing Palestinian officials. Three Israelis have also been killed, with more than 500 rockets fired from Gaza since Wednesday.

Israeli Vice Prime Minister Moshe Yaalon said more than 1,000 Palestinian targets have been hit, “so Hamas should do the math over whether it is or isn't worth it to cease fire.”

"If there is quiet in the South and no rockets and missiles are fired at Israel's citizens nor terrorist attacks engineered from the Gaza Strip, we will not attack," he wrote on Twitter.

The military, on its official Twitter account, said that the sites it hit Saturday night were “all positively identified by precise intelligence over the course of months.”

An Arabic-language recording was repeatedly broadcast over the radio stations of Hamas and the Islamic Jihad militant group, apparently by the Israeli military, warning the people of Gaza to stay away from Hamas installations and personnel.

"To the people of Gaza, Hamas is playing with fire and gambling with your fate," said the message, which was broadcast every five minutes. "The Israeli Defense Force is moving toward the second phase of its operation. For your safety, you should stay away from Hamas infrastructure and personnel."

Though it wasn’t clear what the “second phase” was, thousands of Israeli troops are stationed near the Gaza border apparently awaiting orders for a ground invasion.

The Israeli Cabinet Friday authorized the mobilization of as many as 75,000 reservists to prepare for a possible ground invasion.

Israel killed a Hamas military leader Wednesday, triggering intense fighting. Israel has declared that its goal is to exhaust militant arsenals and thwart cross-border rocket fire by Hamas that has plagued Israeli border towns for years.