By the CNN Wire Staff
NEAR THE ISRAEL-GAZA BORDER (CNN) -- A cease-fire agreement has been reached to end the hostilities in Gaza, Egypt's foreign minister announced Wednesday at a news conference.
The cease-fire was scheduled to take effect at 9 p.m. (2 p.m. ET) Foreign Minister Mohamed Kamel Amr said.
The agreement came hours after militants exploded a bomb on a public transport bus in Tel Aviv, injuring 24 people.
The blast shook up the Israeli public and drew immediate condemnation from world leaders, including U.N. Secretary-General Ban Ki-moon, who called it "shocking." The White House labeled the strike a "terrorist attack," and Secretary of State Hillary Clinton said the United States "stands ready to provide any assistance that Israel requires."
Hamas praised the attack, which struck close to the headquarters of the Israel Defense Forces, or IDF. But the group did not claim responsibility.
"We told you #IDF that our blessed hands will reach your leaders and soldiers wherever they are," the al Qassam Brigades, the military wing of Hamas, said on Twitter. "You opened the Gates of Hell on Yourselves."
Later, in an interview on the Hamas TV station al Aqsa, the group's spokesman Fawzi Barhoum called on Palestinians for more such attacks.
"We need more of these painful strikes inside the depths of Israel, in all the towns and cities and villages of Israel," he said.
Meanwhile, overnight and into Wednesday, Israeli bombs and artillery turned buildings, tunnels and bridges in Gaza into rubble in 100 strikes confirmed by Israeli authorities. Hamas struck back with at least 62 rockets aimed at southern Israel, according to the Israeli military.
Israel launched the conflict eight days ago with a stated goal of ending the frequent rocket attacks on southern Israel from inside Gaza. Hamas officials have termed it a criminal expansion of Israel's occupation of Palestinian territory.
The bus attack happened around noon in a typically quiet neighborhood of Tel Aviv near Israel's Defense Ministry offices. It was the first terror attack in Tel Aviv since 2006, and the first assault on a bus in Israel since August 2011, when a man blew himself up near a bus near Eilat, killing the driver.
In Wednesday's incident, two people told Israeli radio that they saw a man throw a bag into the bus and then run away after the explosion.
Terrorists planted at least two bombs on the bus and fled, Israeli police spokesman Micky Rosenfeld said. Only one of the bombs exploded, blowing out the windows of the bus but leaving the vehicle otherwise intact, he said.
Images on Israeli TV showed white smoke rising from the bus as police and witnesses milled outside. Police cordoned off the street. At least one passenger was taken out on a stretcher.
Rosenfeld said 24 people were wounded, three of them seriously. Aviva Shemer with Ichilov Hospital said pedestrians were among the injured.
One victim was in serious condition with shoulder injuries, while two others suffered moderate injuries from glass fragments. Some of those being treated suffered panic attacks, Shemer said.
Police said Wednesday evening they were seeking at least one and possibly two suspects.
Israeli authorities have stepped up security nationwide, with additional police on the streets and more plainclothes police officers patrolling public areas, Rosenfeld said.
Tel Aviv resident Audrey Shemesh, who lives in an apartment building overlook the scene of the explosion, said the attack had shaken her confidence in peace.
"They want us dead, and this is really sad," Shemesh said of militants battling Israel, "For now I don't see any solution. They don't want to stop this. They just want to go on and on and on. It's really sad because I believe in peace."
Hamas put its own spin on the attack in a banner on al-Aqsa.
"Hamas blesses the suicide bombing and assures that it is a natural response to the massacre of the al-Dalou family and targeting of innocent Palestinian civilians."
Nine members of the al-Dalou family died in an Israeli airstrike on Sunday, provoking outrage among Palestinians.
There was no immediate response from Israeli leaders to the Tel Aviv bus attack Wednesday and it was not immediately apparent whether it could prompt Israel to step up its offensive or unleash the thousands of troops it has massed at the Gaza border in preparation for a possible ground offensive.
Tuesday night, it seemed a cease-fire, or at least a temporary calming of the violence, was imminent.
A senior Hamas official had told CNN that a "calming down" was to take place, and Egyptian President Mohamed Morsy, who has tried to broker a peace deal, said Tuesday that the "travesty of the Israel aggression on Gaza will end in a few hours."
But after a few hours, Morsy's office told CNN not to expect any announcement.
Prior to Wednesday evening's announcement of a cease-fire, Mousa Abu Marzouk, the deputy leader of Hamas in Cairo, blamed Israel for the breakdown in the talks Tuesday.
"The Israelis did not respond last night at our revised conditions relayed to them through the Egyptian intelligence," he said. "Talk of a temporary cease-fire or 'calming down' was brought to the table, yet they escalated their air strikes late last night as we were trying to reach any sort of cease-fire."
Israeli President Shimon Peres, however, said Hamas was asking for conditions that Israel simply cannot meet.
"They want Israel to do nothing. We shall not fly over, we shall not guard the border," he told CNN's Wolf Blitzer. "Many others. The conditions of Israel is basically security conditions. Their conditions are political ones and this is a contradiction."
The IDF said it had targeted "dozens of terror infrastructure sites," overnight, including Hamas' Ministry of Internal Security, which it saw as a "main command and control center."
Forces also took aim at a police compound, a "military hideout," and other targets it linked to what it called Hamas' "terror activity."
The Israeli military also struck a media building, where it said Hamas "deliberately located" an "intelligence operation center," and a system of tunnels used to transport fuel.
Militants lobbed rockets and missiles toward Israel, targeting military bases, radar sites and numerous cities, including Beer Sheva, according to the al Qassam Brigades' Twitter feed.
A rocket alarm howled in the Israeli city of Ashkelon shortly after 7:30 a.m. Wednesday, just minutes after Hamas' TV broadcaster al-Aqsa reported its militants' rockets striking there as well as in the towns of Sderot and Ashdod. CNN's Fred Pleitgen in Ashkelon heard two impacts but could not yet say if the rockets hit anything.
All told, militants had fired 62 rockets from Gaza as of Wednesday afternoon, with 42 landing in Israel, according to the IDF. The Israeli military's Iron Dome defense system intercepted the other 20, the IDF said.
Diplomats working on a cease-fire hope to avoid a repeat of 2008 and 2009, when at least 1,400 people died when Israeli troops invaded Gaza after a similar spate of rocket attacks.
At least 142 people have died in Gaza since the Israeli airstrikes began, according to the Ministry of the Interior in Gaza. Another 1,180 have been injured, the ministry said. In Israel, five people have died and 94 have been wounded, according to authorities.
Clinton shuttled between meetings with Palestinian and Israeli leadership Wednesday, then moved on to Cairo, where she met with Morsy Wednesday night.
She met earlier in the day with Palestinian Authority President Mahmoud Abbas in Ramallah in the West Bank, according to the U.S. Embassy, as well as with Israeli Prime Minister Benjamin Netanyahu in Jerusalem for a second day.
Abbas told Clinton that Gaza is facing a humanitarian crisis and that an immediate cease-fire is needed, according to the official Palestinian news agency WAFA.
Clinton is not expected to travel to Gaza, which is run by Hamas, considered a terrorist organization by the United States and other countries.
Ban also met with Abbas in Ramallah Wednesday morning.
"Today the situation in Gaza is deeply alarming," Ban said, standing next to Abbas at a news conference. "Rockets aimed at military targets inside Gaza are killing and injuring civilians and damaging... civilian infrastructures."
He demanded that diplomacy pave the way forward and called for the emergence of a Palestinian state.
Pope Benedict, speaking from Vatican City, also issued a plea for peace.
"I feel the duty to reiterate once again that hatred and violence are not the solution to problems," he said.
CNN's Ben Brumfield, Dana Ford, Arwa Damon, Ben Wedeman, Christiane Amanpour, Mohamed Fadel Fahmy, Saad Abedine, Sara Sidner, Frederik Pleitgen, Kareem Khadder, Saad Abedine, Ingrid Formanek, Nicki Goulding, Neda Farshbaf, Marilia Brocchetto and Reza Sayah contributed to this report.