Israel resumed combat operations in the Gaza Strip minutes after a temporary pause in fighting expired on Friday morning.
Both Israel and Hamas-affiliated media had earlier reported there had been rockets and guns fired before the 7am (0500 GMT) deadline.
Israel blamed the terror group for breaking the ceasefire.
The halt in fighting began a week ago, on Nov. 24. It initially lasted for four days, and then was extended for several days with the help of mediators from Qatar, Egypt and the US.
During the week-long truce, Hamas and other militants in Gaza released more than 100 hostages, most of them Israelis, in return for 240 Palestinians freed from prisons in Israel.
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