GAZA CITY — Instead of the wedding drums that typically provide the evening soundtrack in this forlorn coastal strip, the black, still air was pierced by gunshots on Thursday, as citizens fired celebratory rounds after the ruling Hamas faction announced that one of its rockets had hit an Israeli aircraft.

The Israel Defense Forces denied the hit, though footage on Hamas television and YouTube appeared convincing. Either way, the reaction was nonetheless emblematic of the latest lopsided battle between this impoverished, intensely crowded and hemmed-in enclave and its militarily mighty neighbor to the north — as was the rat-tat-tat of gunshots being quickly overtaken by the thunder of F-16 strikes across the city.

“The mood of the people is high despite the siege, despite the Israeli aggression,” said Dr. Hassan Khalaf, director of Al Shifa Hospital here, where many of the Palestinian dead and wounded were taken.

“To be killed while smiling or while confident or not confident, the final outcome is death,” Dr. Khalaf added. “At least now we feel like we can injure the Israelis while they try to harm us.”

Nearly four years after Israel’s Operation Cast Lead killed about 1,400 Gazans in three weeks of air and ground assaults in response to repeated rocket fire, this new conflict has a decidedly different feel, and not just because Israel has said that it has tried to limit its attacks to precision strikes.

This time, Israeli forces are fighting a newly emboldened Hamas, supported by the regional powerhouses of Qatar, Turkey and Egypt, and demonstrating its strength compared with a weak and crisis-laden Palestinian Authority.

After months of mostly holding its fire as it struggled to stop other militant factions from shooting rockets across the border, Hamas has responded forcefully to Israel’s killing on Wednesday of its top military commander, Ahmed al-Jabari. It sent more than 300 rockets into Israel over 24 hours, with several penetrating the heart of Israel’s population center around Tel Aviv; three civilians were killed in an apartment building about 15 miles north of Gaza, and three soldiers were wounded in a separate strike.

For Hamas, the goal is not necessarily a military victory, but a diplomatic one, as it tests its growing alliance with the new Islamist leadership of Egypt and other relationships in the Arab world and beyond.

“The conflict shows how much the region has changed since the Arab uprisings began,” said Nathan Thrall, who researches Israel and the Palestinian territories for the International Crisis Group, which works to prevent conflict. “Now when Gaza is under fire, the loudest voices come not from the so-called Axis of Resistance — Iran, Syria and Hezbollah — but from U.S. allies like Egypt and Qatar.”

One possible way out of the crisis, Mr. Thrall suggested, would be a three-party deal in which Hamas vows to contain Gaza’s more extreme elements in exchange for improved trade through Rafah, the border crossing controlled by Egypt, as well as Kerem Shalom, the commercial crossing managed by Israel.

“The new X-factor is that Egypt is now part of that mix,” said David Makovsky of the Washington Institute for Near East Policy. Hamas, he said, hopes the message to Israel will be: “You don’t want to mess with us in Gaza because you’ll hurt your relationship with Cairo.”

President Mohamed Morsi of Egypt has so far rallied to Hamas’s side: he not only recalled his ambassador from Israel but is sending his prime minster, Hesham Qandil, here on to “confirm Egypt’s solidarity with the people of Gaza in the face of the wanton Israeli aggression,” according to a statement from his spokesman on Thursday.

Ismail Haniyeh, the Hamas prime minister, thanked Mr. Morsi in a televised speech on Thursday night “for the quick and brave decisions he made,” adding, “Today’s Egypt is unlike that of yesterday.”

Coming weeks after the emir of Qatar became the first head of state to step foot in Gaza since Hamas took control in 2007, the visit of such a high-ranking Egyptian creates a dilemma for Israel. Intense bombing during or before Mr. Qandil’s visit could be a public relations disaster internationally, but agreeing to a cease-fire without responding harshly to the rocket fire near Tel Aviv and the three civilian deaths near Gaza would be difficult for those at home to swallow.

“If this had happened before, there would have been more pressure on the Palestinians,” said Waleed al-Modallal, a political science professor at the Islamic University of Gaza. “Now the resistance is working freely.”

Not entirely freely. Mourners broke into a jog on Thursday morning as they accompanied Mr. Jabari’s remains from his home to a mosque for his funeral because Israeli planes were dropping bombs nearby. High-ranking Hamas officials were not among the crowds, heeding Israel’s warning to stay out of sight or risk the same fate.

Among the Palestinian fatalities were five children, two men over 55 and a pregnant 19-year-old, according to relatives and Gaza health officials.

“We heard an explosion that shook the house, and in a moment a shell hit the house,” said Um Jihad, the mother-in-law of the pregnant woman, Heba Al-Mash’harawi, and grandmother of one of the babies, 11-month-old Omar.

Furniture and curtains were ablaze in seconds, and the baby suffocated from smoke, family members said.

As bombing continued — a dozen an hour, according to an Israeli military spokesman — schools were closed and most Gazans huddled indoors, some fleeing the harder-hit outskirts of the cities for relatives’ homes in more populated areas.

Amnah Hassan, 53, said 25 people from three generations crowded into the center of the ground floor of their home, away from windows and only venturing out in the late afternoon to buy a battery-operated radio to monitor news when electricity went out.

Israel dropped leaflets warning Gazans to stay away from facilities used by Hamas to store weapons and accused Hamas of using civilians as human shields by setting up such storehouses in residential neighborhoods.

“Their father was killed in Cast Lead, so they are more terrified,” Ms. Hassan said of three of her grandchildren. “In Cast Lead the bombings did not stop. Here, it becomes quiet for a while, then we think it’s going to be quiet, then suddenly the airstrikes resume. We don’t know what’s going to happen later.”

Thursday was the Islamic New Year, but there were no parties here. Normally traffic-clogged boulevards were mostly empty, and marketplaces had shuttered shops instead of shoppers.

“Who will think of eating sweets in these bitter circumstances?” asked Mohammed Elmzaner outside his bakery.