Israeli troops have killed four Palestinian militants in a gunbattle on the Gaza border, Palestinians say.
Witnesses in Hamas-controlled Gaza said the fighting broke out after Israeli armoured vehicles crossed into the territory near Khan Younis.
The Israeli army said its soldiers were trying to stop militants attempting to plant a bomb near the security fence.
Israel and the Islamist movement Hamas agreed a truce in Gaza five months ago but fierce fighting resumed last week.
The four militants, who witnesses said were all from Hamas, were pronounced dead at Nasser hospital in southern Gaza Strip.
An Israeli army spokeswoman said: "This morning, the Israeli Defence Forces identified armed gunmen attempting to place an explosive device near the security fence in the central Gaza Strip."
"Throughout the exchange of fire a number of mortar rounds were fired at IDF forces and an explosive device was detonated."
"The IDF force identified hitting four gunmen. Grenades and various weapons were found on their bodies," the spokeswoman added.
The renewed violence on the Gaza border came as Israel said aid deliveries to the territory would be dependent on a sustained calm.
Israel has kept its border crossings closed since clashes last week when it staged an armed incursion into Gaza and Palestinian militants responded with a barrage of rocket fire.
Israel allowed fuel shipments to resume on Tuesday, after the only power station in the territory ran out of fuel, but food and other humanitarian supplies have not been transferred to Gaza for eight days.
On Tuesday, the UN said it was running out of food aid because of the Israeli blockade and described the situation as "shameful and unacceptable".
A spokesman for the UN relief agency for Palestinian refugees, Unrwa, called the blockade "a physical as well as a mental punishment". Unrwa distributes food to about half of Gaza's 1.5 million inhabitants.
The lights came on again late on Tuesday in Gaza City, which depends on the plant for most of its power, but there were frequent cuts.
Engineers had been planning to turn on one of the three working turbines at the plant and the others when more fuel arrived.
The power station provides nearly a third of the Strip's electricity. Most of the rest comes from Israel.