Palestinian fighters fired several rockets into Israel from Gaza late Sunday despite reports that the Islamist militant group Hamas is seeking an immediate cease-fire.

A Hamas official announced Sunday that Palestinian factions in Gaza have reached an “informal” accord to cease the rocket attacks. The official said the ceasefire is contingent on Israel halting its attacks.

Israeli media say militants fired two rockets at the Israeli coastal city of Ashkelon and launched more at other targets after the reported cease-fire was supposed to begin Sunday evening. No one was injured, and one rocket was intercepted by Israel's Iron Dome missile defense system.

Earlier Sunday, the Israeli military launched an air strike in the Gaza Strip during the region's fourth straight day of violence. Overall, the clashes have claimed the lives of 15 Palestinians, nine Israelis and five Egyptians.

United Nations envoy Robert Serry held talks with government officials in Cairo Sunday in hopes of restoring calm after the killing of the five Egyptian security personnel Thursday as Israeli troops pursued Palestinian attackers on the Israel-Egypt border.

Israeli diplomats also visited the Egyptian capital in an attempt to repair relations with Cairo. The deaths have sparked outrage in Egypt.

U.S. Assistant Secretary of State Jeffrey Feltman also arrived in Cairo to mediate.

Israeli Defense Minister Ehud Barak has expressed regret for the deaths of the Egyptian officers and says Israel will conduct a full investigation with the Egyptian military. Egypt's government says the response is “not enough.”

Palestinian police say Israeli troops arrested scores of Hamas members Sunday in the southern West Bank, hours after rocket attacks from Gaza on Israel's south.

The Israeli military and Palestinian militants have carried out back-and-forth attacks since the deadly Palestinian raids inside Israel near the Egyptian border on Thursday.

Israel says militants in the Hamas-ruled Gaza Strip have fired more than 100 rockets into southern Israel in the past few days. One attack killed an Israeli man. The Israeli air strikes have killed mostly Palestinian militants. Civilians on both sides have been wounded.

The Arab League has condemned the Israeli air assaults. In a statement Sunday, the group called on the U.N. Security Council to take necessary procedures to end the attacks.

Protesters outside the Israeli embassy in Cairo cheered Sunday when a man climbed atop the building and removed the Israeli flag, replacing it with an Egyptian flag.