Israeli air forces launched air strikes across the Gaza Strip late Wednesday, with no immediate reports of injuries.
Israeli air strikes hit a number of military targets across the besieged coastal enclave, as well as a number of open areas.
Strikes hit a site belonging the military wing of Islamic Jihad in Rafah as well as an open area in the southern Gaza Strip.
The empty land that was hit by the air strike was in al-Nasser neighborhood, while it was not clear where in Rafah the military site belonging to the al-Quds Brigades was.
Three rockets were also fired at the Huttein military site belonging to the al-Quds Brigades in the northern Gaza Strip, and no injuries were reported in that strike.
The Israeli air forces also launched a strike on al-Quds Brigades in al-Qara neighborhood in Khan Younis, and another site belonging to the al-Qassam Brigades, the military wing on Hamas, west of Rafah.
Israeli air forces also launched four air strikes against a site belonging to the al-Qassam Brigades site Areen-2 west of Rafah.
Earlier, Israeli air forces bombed a target north of Beit Lahia in the northern Gaza Strip.
Local sources said an Israeli drone fired a rocket at an empty land near a residential area in the northern Gaza Strip neighborhood.
No injuries were reported in any of the strikes.
An Israeli military spokeswoman did not immediately return calls seeking comment.
'Breaking the Silence'
The al-Quds Brigades, the group's armed wing, claimed responsibility for the rocket attacks earlier in the day, which it named "Breaking the Silence."
A spokesman for the al-Quds Brigades said that the group was not breaking the truce between Israel and Hamas, but was merely "responding" to Israeli killings of seven Palestinians in the last two days, including three in Gaza on Tuesday.
Three other Palestinian militant groups also claimed to have participated in the attacks on Israel, including the National Resistance Brigades, the Abu Ali Mustafa Brigades, and the Al-Aqsa Martyrs' Brigade.
Spokesman for the Gaza Strip government Ihab al-Ghussein said that Israel is "responsible for any escalation," warning of the "consequences of any escalation" and reiterating that "resistance is the right of the Palestinian people to defend itself."
Hamas is in control of the Gaza Strip government and maintains a fragile ceasefire with Israel, but other groups occasionally launch attacks.
Israel has repeatedly violated the ceasefire in the last year by launching attacks into the Strip and opening fire on civilians near the border, and militant groups often respond with rocket fire, which mostly falls in open areas.
Israel has also maintained a severe economic blockade on the Gaza Strip's 1.5 million residents since 2006.
The blockade has severely limited the imports and exports of the Gaza Strip and has led to frequent humanitarian crises and hardship for Gazans.
The escalation came just hours after British Prime Minister David Cameron arrived on his first official visit to the region since taking over as premier in 2010.
It was the heaviest barrage of cross-border rocket fire since a major eight-day confrontation in November 2012 between Israel and militants from Gaza's ruling Hamas movement.
An Israeli security source told AFP that militants had fired more than 50 rockets "in close succession," targeting areas all over the south.
Police said the rocket fire fell in several waves along the length of Israel's border with Gaza and that one struck near a public library in the town of Sderot, while another hit near a petrol station in another area.
There were no immediate reports of injuries or damage.
We will respond 'with great force'
The attack began shortly after Netanyahu and Cameron addressed the 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.
"We will continue to strike those who want to harm us, we'll act against them very forcefully," he was quoted as saying in a separate statement communicated by his spokesman Ofir Gendelman.
"This is the biggest attack on Israel since the 2012 Operation Pillar of Defense," the military said on its Twitter feed, referring to the 2012 confrontation which claimed the lives of 177 Palestinians, mostly civilians, and six Israelis.
Speaking to Israel's private Channel 2 television, 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 said.
A day earlier, an Israeli airstrike killed three Palestinians in the southern Gaza Strip, medics said.
The three resistance fighters were killed by the airstrike in southeast Khan Younis near the Sufa crossing.
The al-Quds Brigades said at the time that the militants were affiliated to the group.
"They were in confrontation with the occupation trying to stop the progress of Israeli military vehicles which were approaching the area," the statement said.
The Israeli army said in a statement that "terrorists affiliated with the Palestinian Islamic Jihad in the southern Gaza Strip fired a mortar shell at IDF forces."
"An IAF aircraft responded immediately in order to prevent further attacks on Israeli civilians and targeted the terrorist squad. Direct hits were confirmed, the army statement said.
The airstrikes came after Israeli forces killed three Palestinian civilians in separate incidents across the West Bank on Monday, leading to widespread anger.
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