The World Health Organization (WHO) on Friday lost touch with its staff in Gaza as telecommunications were cut off, said the head of the UN agency.

"We have lost touch with our staff in Gaza, with health facilities, health workers and the rest of our humanitarian partners on the ground," Director-General Tedros Adhanom Ghebreyesus wrote on X.

He expressed "grave concerns" for their safety and the risks to vulnerable patients.

"We urge immediate protection of all civilians and full humanitarian access," he said.

The post came after the Israeli army announced that its ground forces would expand their activities in the Gaza Strip during the night, a signal that a long-feared ground operation may have begun.

Communications and internet services in the Gaza Strip were completely cut off on Friday evening amid heavy Israeli bombing of feeder lines, towers, and networks, the Palestine Telecommunications Company said.

Ooredoo Palestine, a mobile network operator in the West Bank, said its cellphone services were completely cut off from the Gaza Strip on Friday evening.

World leaders "must not" continue to give the green light for "atrocities to be committed" in Gaza, a UK-based aid group warned on Friday, adding that they are "terrified" of what might come next in the conflict.

"As Israel's indiscriminate bombardment continues to intensify, and a large-scale ground operation looks imminent, we have lost all contact with our team in #Gaza this evening," Medical Aid for Palestinians (MAP) CEO Melanie Ward said on X.

Citing MAP official Mahmoud Shalabi, who has been reporting from inside the besieged and bombarded strip, Ward conveyed fears that people in Gaza would suffer "massacres... done in total darkness," as Israel cut off the region's electricity supply.

Tel Aviv also completely cut off communications and internet services in the Gaza Strip on Friday evening amid heavy bombing of feeder lines, towers, and networks, the Palestine Telecommunications Company said.

Touching on civilian deaths in Gaza, which include over 3,000 children, Ward said: "With Gaza now cut off from the world, we are terrified about what comes next."

Calling on the world to "remember their responsibility" to protect Palestinian civilians, she called on world leaders not to continue to "give the green light for atrocities to be committed in Gaza."

"We need a ceasefire now, and an immediate end to these unprecedented horrors," she added.

The conflict in Gaza began on Oct. 7 when the Palestinian group Hamas initiated Operation Al-Aqsa Flood - a multi-pronged surprise attack that included a barrage of rocket launches and infiltrations into Israel by land, sea, and air.

Hamas said the incursion was in retaliation for the storming of the Al-Aqsa Mosque and growing violence by Israeli settlers against Palestinians.

The Israeli military then launched a relentless bombardment of Hamas targets in the Gaza Strip.

Gaza’s 2.3 million residents have been running out of food, water, medicine, and fuel, and aid convoys recently allowed into Gaza have carried only a fraction of what is needed.

Nearly 8,800 people have been killed in the conflict, including at least 7,326 Palestinians and 1,400 Israelis. Some 70% of the deaths in Gaza are women and children, according to official figures.