Gaza City (Palestinian Territories) (AFP) - A six-year-old girl wounded in an Israeli air strike 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.