GAZA CITY, Gaza Strip — Israel unleashed its heaviest air and artillery assault of the Gaza war on Tuesday, destroying key symbols of Hamas control, shutting down the territory's only power plant and leaving at least 128 Palestinians dead on the bloodiest day of the 22-day conflict.
Despite devastating blows that left the packed territory's 1.7 million people cut off from power and water and sent the overall death toll soaring past 1,200, Hamas' shadowy military leader remained defiant as he insisted that the Islamic militants would not cease fire until its demands are met.
The comments by Mohammed Deif in an audiotape broadcast on a Hamas satellite TV channel cast new doubt on international cease-fire efforts. Aides to Palestinian President Mahmoud Abbas said Egypt was trying to bring Israeli and Palestinian delegations together in Cairo for new talks in which Hamas would be presented this time as part of the Palestinian team.
Israel's final objective in Gaza remained unclear a day after Prime Minister Benjamin Netanyahu warned Israelis to be prepared for a "prolonged" war.
Netanyahu is under pressure from hawkish members of his coalition to topple Hamas in an all-out offensive, but has not let on whether he plans to go beyond destroying Hamas rocket launchers, weapons depots and military tunnels used to infiltrate Israel and smuggle weapons.
Dozens of Israeli airstrikes and heavy tank shelling hit areas across Gaza, which was plunged into complete darkness Tuesday night after a strike on its sole power plant set a fuel tank ablaze.
In the sprawling Jebaliya refugee camp in northern Gaza, at least 24 people — 10 of them from the same family — were killed and dozens wounded in a barrage of tank fire, Hamas health officials said.
"Tanks were firing in all directions and shrapnel was flying," said Moussa al-Mabhouh, a volunteer for Gaza's Civil Defense. "Smoke was rising from houses and from nearby workshops."
In one incident, shrapnel from a strike in Jebaliya hit near a car with U.N. markings, killing an employee of a U.N. aid agency and his brother, and wounding the man's 12-year-old son, said agency spokesman Adnan Abu Hasna.
The Israeli military has said it is targeting Hamas command centers, along with rocket launchers and weapons arsenals, but has not provided explanations when asked about specific strikes in which many members of a single family were killed.
On Tuesday, multiple members of at least five families were pulled from the rubble after airstrikes and tank shells struck their homes, including the mayor of the Bureij refugee camp, his 70-year-old father and three relatives, according to Palestinian health officials.
In all, at least 1,229 Palestinians have been killed, including 128 on Tuesday, making it the single deadliest day since the start of fighting on July 8, said Palestinian health official Ashraf al-Kidra. More than 7,000 have been wounded, he said.
Israel says it has lost 53 soldiers, along with two Israeli civilians and a Thai national.
Despite the heavy Palestinian losses, Deif, the commander of the Hamas military wing, said fighting would continue. "There is not going to be a cease-fire as long as the demands of our people are not fulfilled," he said.
Hamas has demanded that Israel and Egypt lift a border blockade they imposed on Gaza after Hamas seized the territory in 2007. Over the past year, Egypt has further tightened restrictions, shutting down hundreds of smuggling tunnels under the Egypt-Gaza border that had provide crucial tax income to Hamas. The closure of the tunnels drove Hamas into a severe financial crisis.
Deif's voice was recognizable in the audio statement on Al-Aqsa TV. He has survived repeated Israeli assassination attempts and has operated from hiding for years.
Al-Aqsa also broadcast a videotape it said showed an infiltration by Hamas fighters into Israel on Monday through a border tunnel. The footage showed armed Palestinians climbing out of a hole in the ground and attacking an Israeli guard post near the border. They were then seen fleeing back down the hole.
The Israeli military said Hamas infiltrated Israeli territory near a communal farm and killed five soldiers on guard nearby. A Hamas gunman was also killed in the attack. Israeli media reported a soldier shot and killed him while he was dragging one of the bodies back to the tunnel.