Israel’s military on Friday ordered all civilians in northern Gaza – a region with a population of about 1.1 million – to evacuate the area within 24 hours.

The United Nations described the order as “impossible” and urged Israel to rescind it, Bloomberg reported.

The announcement came six days after an unprecedented cross-border assault on Israel by Hamas militants in response to which Israel hammered Gaza with air strikes. Over 2,200 persons have been killed in the conflict since then.

On Friday, the Israeli military ordered civilians in Gaza City to move to areas south of Wadi Gaza, which is the southern boundary of the city. It said they should only return when the military makes another announcement allowing them back.

“The Hamas terrorist organisation waged a war against the state of Israel and Gaza City is an area where military operations take place,” the Israel Defense Forces said in its directive to civilians in Gaza City. “This evacuation is for your own safety.”

The country’s military alleged that Hamas militants were hiding in Gaza City inside tunnels underneath houses and inside buildings populated with innocent civilians. It alleged that the militant group was using civilians as human shields.

“In the following days, the IDF [Israel Defense Forces] will continue to operate significantly in Gaza City and make extensive efforts to avoid harming civilians,” the military said.

The United Nations, however, said it was impossible for such a movement to take place without devastating humanitarian consequences.

“The United Nations strongly appeals for any such order, if confirmed, to be rescinded avoiding what could transform what is already a tragedy into a calamitous situation,” it said, according to Bloomberg.

Israel’s ambassador to the United Nations, Gilad Erdan, said the agency’s response to the country was “shameful”. Erdan said the United Nations should focus on condemning Hamas and backing Israel’s right to self-defence.

Hamas, on its part, urged residents of Gaza to defy the order to evacuate their homes, Reuters reported.

“We tell the people of northern Gaza and from Gaza City, stay put in your homes, and your places,” said Eyad al-Bozom, spokesperson for the Hamas interior ministry. “By carrying out massacres against the civilians, the occupation wants to displace us once again from our land.”

The World Health Organization lamented that asking vulnerable patients to evacuate hospitals in Gaza is a “death sentence”. Tarik Jasarevic, a spokesperson for the health body, said that there are severely sick people whose only chances of survival depends on being on life support.

“Hospitals have only a few hours of electricity each day as they are forced to ration depleting fuel reserves and rely on generators to sustain the most critical functions,” he added. “And even those functions will have to cease in a few days when fuel stocks run out.”

On Monday, Israel declared a complete siege of Gaza, intensified airstrikes and sealed it from water, fuel and power supplies. The United Nations has said that the war has internally displaced over 1,23,000 people in Gaza due to concerns about their protection and the destruction of homes.

On Wednesday, electricity in the region went out after the sole power station ran out of fuel.

First batch of Indians returns from Israel

Earlier on Friday, the first batch of Indians who were in Israel returned to New Delhi on a special flight.

India launched an operation on Wednesday to facilitate the return of its citizens from Israel amid the conflict.

The Ministry of External Affairs said that 212 Indians returned to the country on Friday. The ministry said on Thursday that around 18,000 Indians were in Israel, about a dozen were in the West Bank, while three to four were in Gaza.

One of those who returned to India, a post-doctoral researcher named Shashwat Singh, said he hoped peace would return to the region soon, according to PTI. “We woke up to sounds of air raids’ sirens,” he said. “We stay in central Israel. I don’t know what shape this conflict will take... I am doing postdoc in agriculture there.”

Singh thanked Prime Minister Narendra Modi and the Indian Embassy in Israel for arranging for Indian citizens to return home.