“I cannot stress enough the dire consequences of this communications blackout on our ability to provide essential humanitarian aid,” Fikr Shalltoot, director of the Medical Aid for Palestinians group in Gaza, told The Associated Press from Egypt, where she is based. “We cannot communicate with our partners to deliver vital health services. We are unable to even check in with our colleagues, most of whom have been displaced from their homes and lost loved ones.”

The offensive, triggered by the unprecedented Oct. 7 Hamas attack on Israel, has flattened much of northern Gaza and driven 85% of Gaza’s population of 2.3 million from their homes. Displaced people have squeezed into shelters mainly in the south in a spiraling humanitarian crisis.

In their Oct. 7 attack, Hamas militants killed about 1,200 people in Israel, most of them civilians, and took more than 240 hostage.

On Friday, Israeli troops mistakenly shot and killed three Israeli hostages in the Gaza City area of Shijaiyah, where troops have been engaged in fierce fighting with Hamas militants in recent days. The soldiers mistakenly identified the three Israelis as a threat and opened fire, said the army’s chief spokesperson, Rear Adm. Daniel Hagari.

Hundreds of protesters blocked Tel Aviv’s main highway late Friday in a spontaneous demonstration calling for the hostages’ return. The hostages’ plight has dominated public discourse in Israel since the Oct. 7 attack. Their families have led a powerful public campaign calling on the government to do more to bring them home.

Anger over the mistaken killing of the three — young men in their 20s — is likely to increase pressure on the government to renew Qatar-mediated negotiations with Hamas over swapping more captives for Palestinians imprisoned in Israel.

Hamas released over 100 hostages for Palestinian prisoners in November. Nearly all those freed on both sides were women and minors. Talks on further swaps broke down, with Hamas seeking the release of more veteran prisoners for female soldiers it is holding.

Israeli political and military leaders often say freeing all the hostages is their top aim in the war alongside destroying Hamas. However, they argue that their release can only be achieved through military pressure on Hamas, a claim that has sharply divided public opinion.

After negotiations broke down, Hamas said it will only free the remaining hostages, believed to number more than 130, if Israel ends the war and releases all Palestinian prisoners. As of late November, Israel held nearly 7,000 Palestinians accused or convicted of security offenses, including hundreds rounded up since the start of the war.

Residents in northern Gaza meanwhile reported heavy bombing and the sounds of gunbattles overnight and into Saturday in devastated Gaza City and the nearby urban refugee camp of Jabaliya.

“It was a violent bombardment,” Asad Abu Taha said by phone from the Shijaiyah neighborhood, adding that contact with others was difficult because of the telecommunications interruptions. “We don’t know what’s happening.”

Another resident, Hamza Abu Seada, reported heavy airstrikes in Jabaliya, with non-stop sounds of explosions and gunfire.

An Associated Press journalist in southern Gaza also reported airstrikes and tank shelling overnight in the cities of Khan Younis and Rafah.

With only a trickle of aid able to enter Gaza and distribution disrupted by fighting, the U.N.’s World Food Program reported a surge from 38% to 56% in the number of displaced households experiencing severe levels of hunger in the space of under two weeks. In the north, where aid has been unable to enter, “households … are expected to face a catastrophic situation,” the WFP said.

The offensive has killed more than 18,700 Palestinians, the Health Ministry in Hamas-run Gaza said Thursday before the communications blackout. Thousands more are missing and feared dead beneath the rubble. The ministry does not differentiate between civilian and combatant deaths. Its latest count did not specify how many were women and minors, but they have consistently made up around two-thirds of the dead in previous tallies.

On Friday, an Israeli strike killed a Palestinian journalist and wounded another in the southern city of Khan Younis, both working for the Al Jazeera television network. The two were reporting at a school that had been hit by an earlier airstrike when a drone launched a second strike, the network said.

Dozens of mourners held funeral prayers for Samer Abu Daqqa outside Nasser Hospital in Khan Younis, the Qatari network reported. According to the Committee to Protect Journalists, the cameraman was the 64th journalist to be killed since the conflict erupted. The others included 57 Palestinians, four Israelis and three Lebanese.

Khan Younis has been the main target of Israel’s ground offensive in the south.

Responding to accusations that it was deliberately targeting journalists, Israel’s military said it “takes all operationally feasible measures to protect both civilians and journalists. The (Israel Defense Forces) has never, and will never, deliberately target journalists.”

The United States, Israel’s closest ally, has expressed unease over Israel’s failure to reduce civilian casualties and its plans for the future of Gaza, but the White House continues to offer wholehearted support with weapons shipments and diplomatic backing.

In meetings with Israeli leaders on Thursday and Friday, United States national security adviser Jake Sullivan discussed a timetable for winding down the intense combat phase of the war. Secretary of Defense Lloyd Austin was also expected to visit Israel soon to discuss the issue.

The U.S. has pushed Israel to allow more aid into Gaza, and the government said it would open a second entry point to speed up deliveries.