It was meant to be a five hour ceasefire.
But Palestinian militants have fired mortars from Gaza during the halt in hostilities, according to Israel whose military did not immediately respond.
Israel and Hamas had both agreed to hold fire at the request of the UN on humanitarian grounds. The three mortars landed in an agricultural area of Israel and no injuries are reported.
Earlier, Israeli forces said they thwarted a bid by Palestinian militants to infiltrate a kibbutz, by means of an underground tunnel from Gaza.
Israel has released footage which is says shows the foiled attack in which several gunmen were killed.
But it is the deaths of four young boys on a beach in Gaza that has stirred dismay and indignation internationally. Gaza officials say the youngsters from the same family – two aged 10 and the others 9 and 11- were playing when they were killed by shelling from an Israeli gunboat.
The Israeli military said the reported civilian casualties were unintended and “tragic” and that it was investigating what happened.
Gaza officials say some 220 Palestinians have died in ten days of fighting. One Israeli has been killed.