The truce announced late on Thursday night between Israel and Hamas was hanging in the balance on Friday after at least two Palestinians were killed during protests on the Gaza border.
Israeli tanks fired at a Hamas post after Israel said a grenade was thrown at its troops on the border.
Palestinian sources reported that some 100 people were also injured during Friday’s clashes, most from tear gas inhalation.
Hamas officials described the ceasefire, brokered by Egypt and the United Nations envoy to the region, Nickolay Mladenov, as a limited understanding of "calm for calm".
Israel and Hamas have fought three wars over the past decade, in 2008, 2012 and 2014 and an exchange of fire on Thursday was the most intense since the 2014 Gaza war.
After a rocket landed close to Beer Sheba, the largest city in southern Israel, Israel responded by destroying a five-story building in Gaza's Rimal neighbourhood on Thursday evening. Gaza's health ministry said 20 people were wounded in the strike on the premises, which housed both a Hamas internal security office and what Palestinian media said was a culture and sciences centre.
Israel said that in an attempt to minimise civilian casualties, it had warned Hamas shortly before the strike that the building would be targeted.
Hamas denounced the “barbaric” attack as an Israeli ?attempt to undermine the Egyptian mediation efforts.
After a day of militant rocket fire into southern Israel and Israeli airstrikes on Hamas targets in Gaza on Thursday, it appeared that another full-scale conflagration was a distinct possibility, but the sides stepped back from the brink.
According to Israeli media reports, defence minister Avigdor Lieberman was the only member of the security cabinet, which convened on Thursday night, who advocated a large-scale operation, and it was decided to shelve this option for the time being and to try to wear down Hamas with military strikes of limited scope.
Ceasefire efforts
Military officials also reportedly opposed a ground offensive, arguing that it would not significantly improve Israel’s situation, given the working assumption that there is no organisation that could replace Hamas in ruling Gaza at this stage.
But both Israel and Hamas realise that with the incidents of cross-border fire erupting every few weeks it is only a matter of time, and luck, before the exchanges plunge the sides into another war.
Aware of the dangers, Egypt and Mr Mladenov, together with other regional players, have stepped up their efforts over recent weeks to clinch a comprehensive ceasefire package. Elements of the arrangement include an end to militant attacks, including the launching of incendiary kites; Israel releasing Palestinian security prisoners in return for Hamas freeing two Israeli civilians held in Gaza and the remains of two Israeli soldiers; easing the economic siege in stages and opening the Gaza crossings; and a number of long-term projects to improve the humanitarian situation in Gaza.
The long-suffering residents of Gaza need the package to be implemented as soon as possible. The budget of the United Nations relief agency Unrwa is set to run out by September, leaving the prospect of there being no money to distribute food to one million people in need.