GAZA CITY  - Israeli strikes on Gaza killed 15 more Palestinians and destroyed the Hamas government headquarters on Saturday as Israel called up thousands more reservists for a possible ground war.

Israeli warplanes carried out 180 airstrikes overnight levelling the headquarters of the Hamas government.

“It’s like a real-life horror movie, what I saw today ... It’s a miracle we’re still alive,” said 18-year-old Suha, standing in front of her house.

Medics said 45 Gazans have been killed and more than 350 wounded since Israel launched an aerial campaign on the enclave on Wednesday afternoon, with at least five Gaza fighters among the 15 people killed in Saturday’s raids.

As the toll rose, sirens went off in Tel Aviv for a third day running, sending people scuttling for cover, a day after a rocket crashed into the sea near the city centre, AFP correspondents said. The fire was claimed by Hamas’s armed wing.

A statement first announced two deaths in a strike on Deir al-Balah, then added an additional two deaths in a strike on the Masdar area, also in central Gaza. At least four people were injured in the strike in Deir al-Balah, which followed multiple strikes during the day that killed 11 Palestinians.

The statement added that at least two Palestinians were in critical condition after an air strike on their car in the Zeitun neighbourhood of Gaza City, adding that another two were also in serious condition after a strike on a motorbike in Khan Yunis, in central Gaza.

Since the start of Operation Pillar of Defence, the Israeli army says Gaza fighters have fired more than 600 rockets over the border, of which 404 hit and 230 were intercepted by the Iron Dome defence system.

Over the same period, three Israelis have been killed and 18 injured, including 10 soldiers, with the army saying the air force had hit more than 830 targets in Gaza.

On Saturday, four Israeli soldiers and five civilians were hurt in separate rocket attacks on the south which hit a building and a car, police and the army said. Another group in Gaza, Islamic Jihad, claimed those attacks.

The military said it had sealed off all main roads around Gaza and declared a closed military zone, in the latest sign it was poised to launch its first ground offensive on the territory since the 22-day campaign over New Year 2009.

Overnight, the air force hit Gaza City, targeting Hamas prime minister Ismail Haniya’s headquarters, other government buildings, including the interior ministry and police compound, the training facilities and “dozens of terror sites,” it said.

Correspondents at the scene said the headquarters, which had been emptied over attack fears, was reduced to a pile of rubble but there were no reports of casualties.

Air strikes in southern Gaza, notably Rafah, killed six people while three more died in an Israeli raid on a refugee camp in central Gaza, medics said. Another man died of injuries sustained in a morning strike on Gaza City.

Saturday’s violence came as Tunisian Foreign Minister Rafik Abdessalem paid a brief solidarity visit to Gaza, a day after a similar mission by Egyptian Prime Minister Hisham Qandil.

The world must stop Israel’s “blatant aggression,” Abdessalem told AFP on his arrival in Gaza City, where he visited the ruins of the cabinet building where a day earlier Haniya had received Qandil. The Tunisian minister called on the Arab League to act to halt the aggression as it gathered for talks in Cairo.

Egypt and Turkey, meanwhile, put the onus on Israel to end the fighting, as Turkish Prime Minister Recep Tayyip Erdogan visited Cairo a day after Washington urged the two Muslim countries to pressure the Palestinians.

After a meeting with his counterpart Ahmet Davutoglu, Egyptian Foreign Minister Mohammed Kamel Amr said they both agreed on “denouncing Israel’s aggression and on the need to swiftly stop this aggression.”

President Barack Obama reiterated US support for Israel’s right to defend itself during a telephone call with Netanyahu.

Late on Friday, Israeli ministers approved the call-up of as many as 75,000 reservists several hours after Hamas fighters said they fired a rocket at Jerusalem, and another crashed into the sea off Tel Aviv.

The two rockets were the farthest Gaza fighters have ever fired into Israel.

Neither caused any casualties or damage, but they sowed panic in both of the Jewish state’s main population centres, setting off warning sirens and sending people scurrying to shelters.