A fragile lull in fighting between Israel and Palestinian militants in Gaza ended Thursday, as the radical Islamic Jihad faction retaliated for the killing of five of its fighters in the West Bank by firing a new barrage of rockets from the Strip, according to dpa. After six days of relative calm, the Islamic Jihad launched at least 16 self-made al-Quds rockets at southern Israel Thursday, in addition to five mortar shells. Two of the rockets landed in the Israeli town of Sderot, just north-east of Gaza. Israel too launched one airstrike, its first in six days, targeting a rocket launcher near the northern Gaza town of Beit Hanoun before dawn which was loaded and had just been made ready for firing, an Israeli military spokesman said. "There is no room for calm in the shadow of the continuation of the occupation crimes," the Islamic Jihad vowed in a statement. The new violence came after Israeli undercover soldiers in civilian clothes ambushed four Palestinian militants, among them Mohammed Shahadeh, the Islamic Jihad's Bethlehem commander, outside a bakery in the southern West Bank city of Bethlehem. An Israeli military spokeswoman said the Israeli commandos opened fire at the four, who were armed with semi-automatic rifles and pistols but had no chance to draw them. One of the four was a senior militant in the al-Aqsa Martyrs Brigades, but the three others were all of the Islamic Jihad, and Israeli officials said their deaths dealt a serious blow to the radical faction's armed wing in Bethlehem. Another top Islamic Jihad leader - its Tulkarm commander - was killed in the northern West Bank earlier Wednesday. The Israeli military said they were involved in past suicide bombings in Tel Aviv and elsewhere and had been sought by Israel for years. The killings came hours after Hamas leader Ismail Haniya, whose Islamic militant Hamas movement carried out most rocket attacks during five days of heavy fighting earlier this month, called for a "reciprocal, simultaneous and comprehensive" truce with Israel in both Gaza and the West Bank. "The decision to agree on a ceasefire is in the hands of Israel," he said in an address at Gaza's Islamic University, adding the truce should also include an end to Israel's stringent economic embargo on Gaza and a deal that would allow the reopening of its border crossings. Both Israeli Prime Minister Ehud Olmert and Defence Minister Ehud Barak had adamantly denied the existence of a tacit, informal "truce" understanding with Hamas, despite the clear lull in fighting, which came after five days of the deadliest Israeli-Palestinian fighting in Gaza in 40 years early this and late last month. More than 120 Palestinians and 5 Israelis were killed in the fighting.