Israeli warplanes pounded 29 Palestinian targets in the Gaza Strip Thursday night in response to heavy Palestinian rocket fire into the Jewish state earlier, the military said.
Palestinian eyewitnesses, including an AFP photographer, said warplanes hit bases of the strip's Hamas rulers and the armed wing of Islamic Jihad, the Al-Quds Brigades, which had claimed responsiblity for firing dozens of rockets into Israel.
An army statement late Wednesday night said the remains of 60 rockets had so far been located, five of which hit populated areas.
"In response to the massive rocket attack that hit Israel earlier this evening, the Israel Air Force targeted 29 terror sites in the Gaza Strip. Direct hits were confirmed," it said.
"This retaliation was precise and prompt. We targeted the infrastructure that serves the terrorists while they train, plan and implement their hideous attacks," it quoted Lieutenant Colonel Peter Lerner, the chief military spokesman, as saying.
"They will not be permitted to conspire in the safety of their terrorist temples."
Al Quds said it fired 90 rockets at Israel in response to an air strike on Tuesday that killed three of its militants in southern Gaza.
The militant strikes, which sent tens of thousands of Israeli in the south to seek shelter were the biggest wave of attacks since a major eight-day November 2012 confrontation between Israel and Hamas.
There were no immediate reports of casualties on either side Wednesday.
Hamas personnel, including its military wing, the Ezzedine Al-Qassam Brigades, had earlier evacuated all their bases, Gaza security sources said.
The earlier Al-Quds barrage, which Israel said came from several sites, prompted Prime Minister Benjamin Netanyahu to warn of a tough response.
And Washington called for "these terrorists attacks to cease immediately" adding it condemned the rockets from Gaza "in the strongest terms".
The escalation in violence came just hours after British Prime Minister David Cameron arrived on his first official visit to the region since taking office in 2010.
Police raised the level of alert in the south, saying the rockets struck along the length of Israel's border with Gaza.
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One hit near a public library in the town of Sderot, and another near a petrol station.
The attack began shortly after Netanyahu and Cameron addressed parliament, and prompted a stern warning from the Israeli leader, who pledged to act "with great force" against those seeking to harm Israel, a statement from his office said.
Later, Netanyahu warned those in Gaza again.
"If there won't be quiet in the south (of Israel) there will be noise in Gaza, and this is an understatement," he said, in remarks relayed by his office.
It said that he held a telephone conference with defence and security chiefs and instructed them to act "in any way" to restore calm.
Defence Minister Moshe Yaalon ordered the closure from Thursday of the Kerem Shalom goods crossing between Israel and Gaza and the Erez pedestrian crossing "until further security assessments," a military statement said.
"This is the biggest attack on Israel since the 2012 Operation Pillar of Defence," the military said on Twitter, referring to the 2012 confrontation that claimed the lives of 177 Palestinians, mostly civilians, and six Israelis.
- 'Reoccupation' of Gaza -
Foreign Minister Avigdor Lieberman said Israel would have no choice but to reoccupy Gaza, from which it withdrew all troops and settlers in summer 2005.
"Following an attack like this -- a barrage of more than 50 rockets -- there is no alternative to a full reoccupation of the entire Gaza Strip," he told private Channel 2 television.
In Gaza, Islamic Jihad's armed wing the Al-Quds Brigades issued a statement saying its bombardment would continue in response to Israel's "aggression" in Tuesday's air strike.
Hamas warned Israel against escalating the confrontation.
"We hold the occupation responsible, we warn of the consequences of any escalation and we reiterate that resistance is the right of the Palestinian people to defend itself," said Ihab al-Ghassin, a spokesman for the Islamist movement Hamas, which governs Gaza.