GAZA CITY - A six-year-old girl wounded in an Israeli airstrike on the Gaza Strip Saturday has died of her injuries, Palestinian medical sources told AFP, naming her as Israa Abu Khussa.

Her brother Yassin, 10, died earlier in a raid on a base of Hamas's military wing near their home in the northern Gaza village of Beit Lahiya. Another brother, Ayub, 13, suffered moderate injuries. Yassin was buried on Saturday afternoon, when hundreds of mourners attended his funeral, AFP journalists said.

The pre-dawn wave of Israeli air strikes came hours after four rockets fired from the enclave by Palestinian militants hit southern Israel on Friday night without causing casualties, the Israeli army said. "In response to the aggression, the Israel Air Force targeted four Hamas sites in the northern Gaza Strip," a military statement said.

Senior Hamas official Ismael Radwan called the Israeli strikes "an escalation" and placed "full responsibility" on the Jewish state. "The blood of the children killed in the Zionist raid will not flow in vain," the movement's military wing, the Ezzedine al-Qassam Brigades, warned in a statement. Our "patience with the attacks of the enemy has its limits", it added.

Since the end of the devastating war between Israel and Gaza militants in summer 2014, approximately 34 projectiles fired from the Islamist Hamas-controlled coastal strip have hit Israel, according to its military. Sunni Muslim militants claiming links to the Islamic State jihadist group have said they were behind rocket fire in recent months, but Israel holds Hamas responsible for all such incidents.

Moreover, three senior leaders of Palestinian Islamist group Hamas travelled to Cairo on Saturday to try to repair relations with Egypt after years of tension. The visit comes a week after Egypt accused Hamas of involvement in last year's assassination of Public Prosecutor Hisham Barakat. Hamas rejected the claim as "politically motivated". Egypt, historically the Palestinians' major backer, has brokered several truces between Israel and Gaza factions and tried to heal past rifts between rival Palestinian factions.

But it has intensified a blockade of Gaza by largely sealing the border since 2013, citing precarious security conditions in neighbouring Sinai where Islamist militants have launched many deadly strikes on Egyptian soldiers. The 12-member Hamas delegation headed for Cairo included three top figures, Mahmoud Al-Zahar, Khalil Al-Hayya and Imad Al-Alami. An Egyptian border official told Reuters they were escorted under heavy security.

Hamas spokesman Sami Abu Zuhri said the officials were hoping to turn a new page in relations with Egypt. "Hamas stresses its interest in preserving the security and stability of Egypt and we are looking forward to a new era in relations," he said in a statement.

Egyptian and Israeli blockades of Gaza have made it difficult for goods and people to move in and out of the territory, increasing hardship for its 1.95 million people. Hamas wrested control of the territory in a brief 2007 civil war with forces loyal to Western-backed Palestinian President Mahmoud Abbas, who holds sway in the occupied West Bank.

Its relations with Cairo have worsened since 2013, when Egypt's army ousted Islamist leader Mohamed Mursi, the country's first elected president. Mursi's Muslim Brotherhood was Hamas's strategic ideological ally. Some Cairo security officials have accused Hamas of aiding militants in Sinai, but Hamas leaders have repeatedly denied meddling in Egypt's internal affairs. Gaza security sources told AFP that Mahmud Zahar, Khalil al-Haya, Imad al-Alami and Nizar Awadallah passed through the southern Gaza Rafah terminal, the only crossing point with the enclave not controlled by Israel. They were heading to Cairo for talks with intelligence chiefs on relations between the sides.

Former army chief Abdel Fattah al-Sisi, who deposed Morsi, won presidential elections in 2014 on a pledge to wipe out Islamist militants. The militant Islamic Hamas, which rules Gaza, has its origins in the Muslim Brotherhood movement which is outlawed in Egypt. On Sunday, Egypt's Interior Minister Magdy Abdel Ghaffar said both organisations were involved in last year's assassination of the country's top prosecutor.

Since taking office, the Sisi government has accused Hamas of aiding jihadist groups in the Sinai Peninsula who have repeatedly attacked Egyptian security forces. Egypt has largely kept its border with Gaza closed since 2013 and has destroyed hundreds of Palestinian tunnels under the frontier used to smuggle commercial goods, cash, people and, allegedly, weapons.