Four soldiers were injured when an anti-tank missile fired from the Gaza Strip struck and penetrated an Israeli army jeep patrolling some 200 meters inside the Israeli border with Gaza on Saturday evening.

Two of the four were in serious condition and underwent surgery on Saturday night. One of them remained in critical condition, the other was stabilized.

Retaliatory strikes by the IDF against terrorists in the Gaza Strip left at least four Palestinians killed and two dozen wounded.

Later Saturday, a rocket barrage fired from Gaza pounded southern Israel; residents were ordered to stay within 15 seconds of sealed rooms or other protected areas. No major damage or injuries were reported. Red Alert sirens sounded as far north as the cities of Ashdod and Gan Yavne after long-range Grad rockets were fired in their direction.

A statement issued by Hamas, which rules Gaza, said all Israeli military targets were “legitimate” objects of attack.

A senior Islamic Jihad official said that Gaza terrorist groups “will not give the Zionist enemy calm for free.”

“The Resistance can not sit idly by. Our message to the foe is that it will be bombardment for bombardment, blood for blood,” Mahmoud Madlal said.

IDF Chief of Staff Lt.-Gen. Benny Gantz convened with Prime Minister Benjamin Netanyahu and Defense Minister Ehud Barak late Saturday to assess the situation along the border and discuss the escalation of violence. Israel’s Channel 2 said Gantz had ordered a “speeding up of preparations” for further conflict. The TV report noted that recent cross-border fire from Gaza had included highly accurate Katyusha rockets, capable of doing far more damage than previous rocket fire.

Of the soldiers injured, the IDF said one was seriously hurt with shrapnel wounds to the head, another was also in serious condition and two were moderately injured when their Givati Brigade vehicle was hit by the missile near the Karni border crossing. The two seriously injured soldiers were airlifted to Soroka Medical Center in Beersheba and the two moderately wounded soldiers were rushed to Barzilai Medical Center in Ashkelon.

Channel 10 reported that an initial investigation conducted by GOC Southern Command Maj. Gen. Tal Russo found that the vehicle was approximately 200 meters from the border fence when it was hit.

The Abu Ali Mustafa Brigades, the armed wing of the Popular Front for the Liberation of Palestine (PFLP), claimed responsibility for the anti-tank missile attack shortly afterwards, saying it fired two Kornet missiles at the Israeli vehicle.

The IDF and Israeli media reports were skeptical about the PFLP’s claim, and instead posited that the likely perpetrator of the attack was Islamic Jihad.

Later, Al Arabiya reported that the armed wing of Hamas, the Izz al-Din al-Qassam Brigades, claimed responsibility for the attack, saying it was in response to the death of a Gaza teen two days before.

Palestinian eyewitnesses reported clashes between Palestinians and IDF troops, and local media reports claimed that the IDF immediately retaliated with tank fire and helicopter strikes that killed four Palestinians and injured at least 25 others.

Ashraf al-Kadera, a Gaza Hamas Health Ministry spokesman, claimed all four killed were civilians between the ages of 16 and 18 and that among the wounded were children.

Four more Palestinians were injured in an IDF airstrike east of Khan Yunis in the southern Gaza Strip, Ma’an news agency reported.

A Southern Command officer told Channel 10 after the attack that “we cannot continue to restrain ourselves with these in incidents in the South. In the past few weeks there has been a rise in the number of wounded as a result of terror activities. If we continue to use restraint and not deal out harder hits, the injuries are likely to continue, and their strength is likely to increase.”

A Hamas spokesman, Fawzi Barhoum, said Saturday that his movement would retaliate against the “Zionist escalation.”

“Our resistance to the occupation and the Zionist soldiers killing our people is legitimate as defense of our families,” Barhoum said, asserting that the Israeli attack came as part of the election campaign.

“We will not allow Palestinian blood to be the price for electoral and political achievements in Israel,” Barhoum told local media.

The clashes came two days after Israeli forces found a large tunnel filled with explosives burrowed beneath the Gaza border fence, and briefly sent ground troops into Gaza. After the IDF disarmed charges found on the Gaza side of the border, explosives in the tunnel exploded, damaging a jeep and lightly injuring a soldier.

In June 2006, Palestinian terrorists crossed into Israel from Gaza via an underground tunnel near the Kerem Shalom Crossing, attacked an Israeli army position, killed two soldiers and captured a third, Gilad Shalit. Shalit was dragged back into Gaza and held captive by Hamas for more than five years. He was released in a lopsided prisoner exchange in October 2011 under which Israel also freed more than 1,000 Palestinian security prisoners.

Hamas and other Gaza terror groups have repeatedly vowed to kidnap more Israeli soldiers in order to pressure Israel into releasing further security prisoners, including the orchestrators of major suicide attacks in Israel whom Israel balked at releasing in the Shalit exchange.