Israel's military on Friday said it had resumed battle in Gaza, as airstrikes and artillery fire reported in Gaza City.
It has begun as soon as the truce expired with no agreement to extend it.
"Hamas violated the operational pause, and in addition, fired toward Israeli territory," the Israeli military said, reports AFP.
"The IDF (Israel Defense Forces) has resumed combat against the Hamas terrorist organisation in the Gaza Strip."
The announcement came shortly after the military said it had intercepted a rocket fired from Gaza, the first from the territory since a missile launched minutes into the first day of the truce.
Inside Gaza, an AFP journalist said Israeli warplanes carried out a series of strikes, and reported artillery fire in Gaza City.
Drones could also be heard in the air over the south of the territory for the first time since the truce, an AFP reporter in the area said.
The resumption of fighting dashed hopes for an extension of a seven-day truce that had seen dozens of hostages freed in exchange for Palestinian prisoner releases by Israel.
The truce also allowed more aid into the ravaged Gaza Strip.
On Thursday, US top diplomat Antony Blinken, meeting Israeli and Palestinian officials, called for the pause in hostilities to be extended, and warned any resumption of combat must protect Palestinian civilians.
The truce had paused fighting that began on October 7 when Hamas militants broke through Gaza's militarised border into Israel.
The surprise attack killed 1,200 people, mostly civilians, and militants kidnapped about 240, according to Israeli authorities.
Israel vowed to eliminate Hamas in response and unleashed an air and ground military campaign in Gaza that the Hamas government says has killed more than 15,000 people, also mostly civilians.
During the truce brokered by Qatar, 80 Israeli hostages were freed in exchange for 240 Palestinian prisoners.
More than 20 foreigners, most of them Thais living in Israel, were freed outside the scope of the agreement.
Overnight, six more Israelis, some holding dual nationality, were released, hours after two women were freed.
That brought the total freed Thursday to eight, less than the 10 hostages a day the truce deal required Hamas to release. A source close to the militant group said it was counting two Russian-Israeli women released on Wednesday as part of the seventh batch.
The release brought relief for Keren Shem, whose daughter Mia was among those freed. The family released footage showing Keren weeping with joy as she was informed by phone of her daughter's imminent freedom.
"Mia is coming back," she cried out.
Bd-pratidin English/Lutful Hoque
