Approximately 250 rockets have been fired by Gaza militants towards Israel, which has responded with airstrikes on more than one hundred targets across the coastal enclave, according to the Israel Defense Forces (IDF).

In response to the rockets, the IDF said it has carried out airstrikes on about 130 militant targets in Gaza, including a tunnel, rocket launcher sites and other military compounds used by Hamas and Islamic Jihad.

Four Palestinians have been killed in the airstrikes, including a 14-month-old child and the child's pregnant mother, Gaza health officials said.

Two men were killed in separate strikes, and 18 other Palestinians have been injured, Gaza health officials said.

Turkey has condemned a strike on a building housing the office of its state-run Anadolu news agency, a building which Israel says is also used by Hamas's military intelligence.

A spokesman for Turkey's President said, “We urge all governments that claim to defend press freedom, including @USEmbassyTurkey to join us in condemning the Israeli government.”

Two Israelis have been wounded in the rocket attacks according to Israel's emergency response service, Magen David Adom.

An 80-year old woman in the city of Kiryat Gat, about 20 kilometres (about 12 and a half miles) from Gaza, suffered shrapnel injuries to her head and legs, and a 49-year old man in Ashkelon, just north of Gaza, was moderately wounded by shrapnel, emergency response officials said. Israel announced that it is closing the two border crossings between Israel and Gaza, as well as closing the Gaza fishing zone.

The fishing zone was restricted to 6 nautical miles earlier this week following a rocket fired from Gaza that landed off the coast of Israel. There was no specific date for when the crossings and the fishing zone would reopen.

Saturday's rocket barrage comes less than a day after two militants from Hamas’ armed wing, the Qassam Brigades, were killed in an Israeli strike on Hamas posts in Gaza.

Israel launched airstrikes Friday after two Israeli soldiers were wounded by sniper fire along the Gaza border.

Two other Palestinians died in Gaza Friday, according to the Palestinian Ministry of Health, with both men succumbing to their wounds after being shot by Israeli troops during protests along the Gaza fence, according to health officials.

This is the first serious escalation between Israel and Gaza militants since the Israeli election almost a month ago. In the run-up to that election, Egypt succeeded in mediating an agreement between Israel and Hamas, the militant group that runs Gaza, following an exchange of rockets and airstrikes in March.

The agreement, though never publicly acknowledged by Israel, included measures aimed at loosening the restrictions imposed on Gaza's 2 million inhabitants.

Recent pronouncements by Hamas officials have suggested growing frustration that Israel has not moved fast enough to fulfil its pledges, including allowing the transfer of millions of dollars of extra funding from Qatar.

Israel also is preparing to mark Independence Day next week and host the Eurovision Song Contest the following week.

Analysts say Israel's Prime Minister Benjamin Netanyahu would much prefer those events to occur in a state of calm rather than one of open conflict.

The UN's Special Coordinator for the Middle East Peace Process, Nickolay Mladenov, announcing renewed efforts with Egypt to restore calm, called on all parties to immediately de-escalate or risk a conflict with “grave consequences for all.”