The Israeli military unleashed a wave of heavy airstrikes on the Gaza Strip early Monday, saying it destroyed 15 kilometers (nine miles) of militant tunnels and the homes of nine Hamas commanders.

Residents of Gaza awakened by the overnight barrage described it as the heaviest since the war began a week ago, and even more powerful than a wave of airstrikes in Gaza City the day before that left 42 dead and flattened three buildings. That earlier attack was the deadliest in the current round of hostilities between Israel and Gaza’s Hamas rulers.

There was no immediate word on the casualties from the latest strikes. A three-story building in Gaza City was heavily damaged, but residents said the military warned them 10 minutes before the strike and everyone cleared out. They said many of the airstrikes hit nearby farmland.

Gaza’s mayor, Yahya Sarraj, told Al-Jazeera TV that the strikes had caused extensive damage to roads and other infrastructure. “If the aggression continues we expect conditions to become worse,” he said.

Read:AP’s top editor calls for probe into Israeli airstrike

The U.N. has warned that the territory’s sole power station is at risk of running out of fuel, and Sarraj said Gaza was also low on spare parts. Gaza already experiences daily power outages for between eight and 12 hours and tap water is undrinkable. Mohammed Thabet, a spokesman for the the territory’s electricity distribution company, said it has fuel to supply Gaza with electricity for two or a three days. Airstrikes have damaged supply lines and the company’s staff cannot reach areas that were hit because of continued Israeli shelling, he added.

The war broke out last Monday, when the Hamas militant group fired long-range rockets at Jerusalem after weeks of clashes in the holy city between Palestinian protesters and Israeli police. The protests were focused on the heavy-handed policing of a flashpoint sacred site during the Muslim holy month of Ramadan and the threatened eviction of dozens of Palestinian families by Jewish settlers.

Since then, the Israeli military has launched hundreds of airstrikes that it says are targeting Hamas’ militant infrastructure. Palestinian militants in Gaza have fired more than 3,100 rockets into Israel.

At least 198 Palestinians have been killed in the strikes, including 58 children and 35 women, with 1,300 people wounded, according to the Gaza Health Ministry. Eight people in Israel have been killed in rocket attacks launched from Gaza, including a 5-year-old boy and a soldier.

“I have not seen this level of destruction through my 14 years of work,” said Samir al-Khatib, an emergency rescue official in Gaza. “Not even in the 2014 war,” he added, referring to the most destructive of the previous three wars fought between Israel and Hamas.

The military said it struck nine houses in different parts of northern Gaza that belonged to “high-ranking commanders” in Hamas, the Islamic militant group that has controlled the territory since seizing power from rival Palestinian forces in 2007.

In recent days, Israel has targeted the homes of a number of senior Hamas leaders, including Yehiyeh Sinwar, the top leader inside Gaza. The group’s leadership goes underground when the fighting begins, and it’s unlikely any were at home at the time of the strikes.

Hamas and the Islamic Jihad militant group say at least 20 of their fighters have been killed, while Israel says the number is much higher and has released the names of and photos of more than two dozen militant commanders it says were “eliminated.”

Read: AP 'horrified' by Israeli attack on its office

The military said it struck 35 “terror targets” as well as the tunnels, which it says are part of an elaborate system it refers to as the “Metro,” used by fighters to take cover from airstrikes.

Despite international efforts at a cease-fire, Israeli Prime Minister Benjamin Netanyahu said Sunday that Israel’s attacks were continuing at “full-force” and would “take time.“ Israel “wants to levy a heavy price” on the Hamas militant group.

Hamas’ top leader Ismail Haniyeh, who is based abroad, said the group has been contacted by the U.S., Russia, Egypt and Qatar as part of cease-fire efforts but “will not accept a solution that is not up to the sacrifices of the Palestinian people.”

In an interview with the Lebanese daily Al-Akhbar, he blamed the war on Israel’s actions in Jerusalem and boasted that the rockets were “paralyzing the usurping entity (Israel) by imposing a curfew on its citizens and closing its airports and ports.”

Egyptian President Abdel Fattah el-Sissi said his government is working to “urgently” end the violence, in his first comments since the war broke out. Egypt, which borders Gaza and Israel, has played a central role in the cease-fires brokered after previous rounds of fighting.

An Egyptian diplomat said the efforts were focusing on two issues — a halt in all attacks from both sides and halting Israeli policies in the contested city of Jerusalem that helped spark the fighting. These include police raids against Palestinian protesters in and around the Al-Aqsa Mosque and the planned evictions of Palestinians by Jewish settlers in east Jerusalem.

The diplomat, speaking on condition of anonymity because he was talking about confidential diplomatic discussions, said mediators were counting on the Biden administration to put pressure on Israel to stop its offensive and there were expectations for action in the coming 48 hours.

Israel’s airstrikes have leveled a number of Gaza City’s tallest buildings, which Israel alleges contained Hamas military infrastructure. Among them was the building housing The Associated Press Gaza office and those of other media outlets. The Israeli military alerted staff and residents before the strike, and all were able to evacuate the building safely.

Sally Buzbee, the AP’s executive editor, has called for an independent investigation into the airstrike.

Read:AP statement on Israeli attack on building housing AP office

Netanyahu alleged that Hamas military intelligence was operating inside the building and said Sunday any evidence would be shared through intelligence channels. Neither the White House nor the State Department would say if any had been seen.

The AP had operated from the building for 15 years, including through three previous wars between Israel and Hamas. The news agency’s cameras, operating from its top floor office and roof terrace, offered 24-hour live shots as militant rockets arched toward Israel and Israeli airstrikes hammered the city and its surroundings.

AP President and CEO Gary Pruitt released a statement after Saturday’s attack saying he was “shocked and horrified” that Israel targeted the building. He said the AP had “no indication Hamas was in the building or active in the building.”

“This is something we actively check to the best of our ability,” he said. “We would never knowingly put our journalists at risk.”