Gaza City - A three-day Gaza cease-fire went into force on Friday as diplomats worked to broker a lasting truce in the 25-day-old Israel-Hamas war, but Gaza officials said the lull was broken after nearly two hours when Israeli tank fire killed at least four Palestinians.
The cease-fire, announced by the US and the UN hours earlier, took effect at 08:00 a.m. (0500 GMT) Friday after heavy fighting that killed 17 Palestinians and five Israeli soldiers. Israel and Hamas agreed to halt all aggressive operations and conduct only defensive missions.
But US Secretary of State John Kerry cautioned there were "no guarantees" that the lull would bring an end to the war, now in its fourth week.
Shortly before 10:00 Israeli tanks shelled the eastern part of the town of Rafah in southern Gaza, killing at least four people and wounding 15, said Health Ministry official Ashraf al-Kidra and Gaza police spokesman Ayman Batniji.
An Israeli Army spokesperson said a heavy exchange of fire had erupted in the Rafah area, without providing further details.
The Gaza war has killed more than 1 450 Palestinians, mainly civilians, and more than 60 Israelis, nearly all soldiers.
Israel launched an aerial campaign against Gaza aimed at halting Palestinian rocket fire on 8 July and later sent in ground troops to target launch sites and tunnels used by Hamas to carry out attacks inside Israel.
At least four short humanitarian cease-fires have been announced since the conflict began, but each has been broken within a few hours by renewed fighting. Friday's temporary cease-fire was the longest to be announced thus far.
Under the cease-fire, Israeli troops on the ground in Gaza can continue to destroy tunnels along the heavily guarded frontier, but only those that are behind Israeli defensive lines and lead into Israel.
Israeli Prime Minister Benjamin Netanyahu on Thursday had vowed to destroy Hamas' tunnel network "with or without a cease-fire." But military spokesperson Moti Almoz told Army Radio on Friday that Israel would not be able to eliminate the tunnel threat "100%".
The cease-fire was intended to allow Palestinians in Gaza to receive food, medicine and humanitarian assistance, bury their dead, treat the wounded and travel to their homes. The lull can also be used to make repairs to water and power infrastructure.