CAIRO — American efforts to help negotiate a cease-fire between Israel and Palestinian militants in the week-old Gaza rocket battle faced a new obstacle on Wednesday when the first bus bombing in years traumatized Tel Aviv, raising the prospect of a new Israeli retaliation just as Secretary of State Hillary Rodham Clinton was working to achieve even a brief pause in the fighting.
Mrs. Clinton, who rushed to the Middle East late Tuesday in an intensified diplomatic push, delayed her departure from Cairo on Wednesday because of intensive consultations with Egypt’s President Mohamed Morsi, his aides, and United Nations Secretary General Ban Ki-moon. Mrs. Clinton came to the Egyptian capital after talks with Israeli leaders in Jerusalem and Palestinian leaders in the West Bank.
Mr. Ban, who made an early exit from the talks, told reporters in Cairo that the Tel Aviv bus bombing had been “designed to test the resolve” of the negotiators and “made it all the more urgent to reach a cease-fire.”
Mr. Morsi’s good relationship with the Hamas government in Gaza has emerged as pivotal to the negotiations that were under way at his presidential offices.
The Tel Aviv bus bombing, which happened near Israel’s Defense Ministry building and wounded at least 21 Israelis in an act that at least two Palestinian militant factions took responsibility for, resurrected fears in Israel of past Palestinian uprisings. It followed Israeli airstrikes overnight and into Wednesday on government buildings in Gaza and suspected smuggling tunnels under Gaza’s Rafah border crossing with Egypt, among other targets.
The back-and-forth attacks emphasized the underlying problems in finding any lasting solution to a conflict rooted in deep-seated hostilities and mistrust between Israelis and Palestinians.
Egyptian and American officials in Cairo said negotiations over a cease-fire, which the Egyptian media and Hamas officials had said was on the verge of completion Tuesday, had been hung up on a number of issues, including Hamas’s demands for unfettered access to Gaza via the Rafah crossing and other steps that would ease Israel’s economic and border control over other aspects of life for the more than one million Palestinian residents of Gaza, which Israel vacated in 2005 after 38 years of occupation.
The Hamas Health Ministry in Gaza said the Palestinian death toll after a week of fighting stood at 140 at noon. At least a third of those killed are believed to have been militants. On the Israeli side, five Israelis have been killed, including one soldier.
Around noon on Wednesday in the Gaza Strip, according to the Hamas government media office, a bomb hit the house of Issam Da’alis, an adviser to Ismail Haniya, the Hamas prime minister. The house had been evacuated. Earlier, a predawn airstrike near a mosque in the Jabaliya refugee camp killed a 30-year-old militant, a spokesman said, and F-16 bombs destroyed two houses in the central Gaza Strip.
There were 23 punishing strikes against the southern tunnels that are used to bring weapons as well as construction material, cars and other commercial goods into Gaza from the Sinai Peninsula.
Within Gaza City, Abu Khadra, the largest government office complex, was obliterated overnight. Businesses were also damaged, including two banks and a tourism office, and electricity cables fell on the ground and were covered in dust.
Separately, a bomb dropped from an F-16 created a 20-foot-wide crater in an open area in a stretch of hotels occupied by foreign journalists. Several of the hotels had windows blown out by the strike around 2 a.m., but no one was reported injured. By morning, the hole in the ground had filled with sludgy water, apparently from a burst pipe, appearing almost like a forgotten swimming hole with walls made of sand and cracked cinder block.
Surveying damage near a government complex, Raji Sourani of the Palestinian Center for Human Rights said Gaza civilians were “in the eye of the storm,” and accused Israel of “inflicting pain and terror” on them. Israeli officials accuse Hamas of locating military sites in or close to civilian areas.
Overnight, as the conflict entered its eighth day, the Israeli military said in Twitter posts that “more than 100 terror sites were targeted, of which approximately 50 were underground rocket launchers.” The targets included the Ministry of Internal Security in Gaza, described as “one of Hamas’s main command and control centers.”