The rocket attacks from Hamas militants in Gaza never ceased, Israeli officials said. For its part, Israel refrained from airstrikes for about six hours before announcing it was resuming the attacks.
A CNN crew witnessed at least five Israeli airstrikes just as the announcement was made.
The Israel Defense Forces said 47 rockets were fired into Israel during the cease-fire period, which Hamas never accepted.
The faltering of the cease-fire attempt means there may be little hope of seeing an end to the near constant exchange of fire that has so far killed more than 190 Palestinians in Gaza.
Israeli leaders had agreed to the cease-fire, but from the outset warned it would be short-lived if the attacks from Gaza didn’t stop.
The Israeli Security Cabinet met early Tuesday morning and decided to halt aerial strikes beginning at 9 a.m. (2 a.m. ET). It resumed strikes about six hours later, by 3 p.m. (8 a.m. ET).
The Egyptian plan calls for all sides to cease hostilities in Gaza. It also calls for the opening of border crossings, once the security situation is stable, and for high-level talks among those involved.
When the plan was announced, there was a split reaction from Hamas. Its military wing rejected any possibility of a cease-fire, while its political wing had said it was considering it.
The stakes are high and climbing.
By Tuesday, the death toll from a week of Israeli airstrikes on Gaza had reached 194 with at least 1,400 wounded, according to Palestinian health authorities.
The death toll is now greater than the number of people killed in Gaza during the 2012 conflict between Israel and Hamas.
Amid the diplomatic maneuvering, the residents of Gaza are stuck in the middle of the continued fighting. The United Nations has said that most of the people killed by Israel’s aerial attacks are civilians.
“I urgently call on the Israeli Security Forces to put an end to attacks against, or endangering, civilians and civilian infrastructure which are contrary to international humanitarian law,” said Pierre Krahenbuhl, commissioner general of the United Nations Relief and Works Agency for Palestine Refugees, or UNRWA.
There are now 17,000 refugees taking shelter in 20 schools in Gaza, UNRWA said, and the airstrikes have damaged 47 of its buildings, including clinics, schools and warehouses.
The Israeli military says it uses a variety of methods, including phone calls and leaflets, to warn civilians of impending strikes.
But UNRWA called on Israel to exercise maximum restraint and precautions to avoid more casualties.
“Clearly at this stage not enough is being done in that regard,” Krahenbuhl said.
Kerry delays trip
U.S. Secretary of State John Kerry was preparing a possible trip to the Middle East to lay groundwork for a cease-fire, but he postponed the visit to give Egyptian efforts a chance to take root.
One official said the United States wants to give Egypt a chance to reassert itself as a power broker in the Middle East, as it did during the 2012 cease-fire.
Kerry continued to follow that line Tuesday.
“The Egyptian proposal for a cease-fire and negotiations provides an opportunity to end the violence and restore calm,” Kerry said from Vienna, Austria. “We welcome the Israeli Cabinet’s decision to accept it. We urge all other parties to accept the proposal.”
Kerry strongly condemned the rocket launches by Hamas in the face of the cease-fire plan, and said he is prepared to fly to the Middle East as early as Wednesday, if needed.
The current Egyptian President, the ex-military chief Abdel Fattah el-Sisi, has weaker relations with Hamas than former President Mohamed Morsy, who brokered the 2012 deal. Morsy was ousted by the military in 2013.
Earlier, Kerry spoke by phone with Israeli Prime Minister Benjamin Netanyahu and expressed U.S. concerns about escalating tensions. He reiterated that the U.S. is prepared to help bring about a cease-fire, a senior State Department official said.
But “offering facilitation is not enough,” Yousef Munayyer of the Washington-based Palestine Center told CNN’s “New Day.”
“It’s important that the United States demand a cease-fire,” he said. “There is no military solution to this.”