KHAN YOUNIS, Gaza Strip (AP) — The Israeli army ordered a mass evacuation of Palestinians from much of Khan Younis on Monday, a sign that troops are likely to launch a new ground assault into the Gaza Strip’s second-largest city.

The order suggests Khan Younis will be the latest target of Israel’s raids into parts of Gaza it had previously invaded in the war as it pursues regrouping Hamas militants. Much of Khan Younis was destroyed in a long assault earlier this year, but large numbers of Palestinians had moved back to escape another Israeli offensive in Gaza’s southernmost city, Rafah.

The evacuation came as Israel released the director of what was once Gaza’s largest hospital after holding him for seven months without charge or trial. Israel alleged the hospital had been used as a Hamas command center, which he and other Palestinian health officials have denied. The doctor said he and other detainees were held under harsh conditions and tortured.

The decision to release Mohammed Abu Selmia raised questions over Israel’s claims surrounding Shifa Hospital, which Israeli forces have raided twice since the start of the war with Hamas. The hospital was left severely damaged after the raids.

Abu Selmia's release triggered an uproar across Israel’s political spectrum. Prime Minister Benjamin Netanyahu's office called it “a grave mistake.” Government ministers and opposition leaders expressed outrage and insisted Abu Selmia played a role in Hamas’ alleged use of the hospital — although Israeli security services rarely unilaterally free prisoners if they have a suspicion of militant links.

Khan Younis evacuation

Monday’s evacuation order covered the eastern half of Khan Younis and a large swath of the Gaza Strip’s southeast corner. Earlier in the day, the army said a barrage of rockets out of Gaza was fired from Khan Younis.

As night fell, streams of civilians trudged on foot beside a steady flow of vehicles as people began making their way out of the evacuation zone. A woman dragged a rolling suitcase with a little girl riding on top. Others carried a few crucial belongings — mattresses, clothing, plastic buckets for washing, an electric fan. Trucks were piled high with possessions and furniture.

“We received a message on our mobile phones” to evacuate, said one displaced woman, Zeinab Abu Jazar, holding back tears. “Look at these children, how they walk. We did not find a car to ride in.”

Israel told people to move to Muwasi, a coastal area designated by the Israeli army as a safe zone and which has become filled with crowded and unsanitary tent camps.

The order suggested a new assault into Khan Younis was imminent. Israeli forces fought for weeks in Khan Younis earlier this year and withdrew, claiming to have destroyed Hamas battalions. But in other places where the military has made similar claims, renewed raids have underscored Hamas’ capabilities.

Last week, the military ordered an evacuation from the north Gaza district of Shijaiyah, and intensive fighting has followed.

Netanyahu said Monday that the military was “making progress toward ending the phase of the destruction of Hamas’ terror army.” But he said forces will continue to “target their remains going forward.”

More fighting in the Khan Younis area could further hamper Palestinians’ access to much-needed potable water. Included in the evacuation zone is a water line that Israel installed following criticism over its cutoff of water to the strip early in the war.

Also in the zone is the area surrounding the Kerem Shalom crossing, the major aid crossing to southern Gaza, and an aid route inside the territory that Israel has said it would safeguard.

Most of Gaza’s population of 2.3 million have fled their homes, with many displaced multiple times. Israeli restrictions, fighting and the breakdown of public order have hindered the delivery of humanitarian aid, fueling widespread hunger and sparking fears of famine.

U.N. Secretary-General Antonio Guterres said the new evacuation order “just shows yet again that no place is safe in Gaza” for Palestinian civilians. “It’s another stop in this deadly circular movement that the population in Gaza has to undergo on a regular basis,” he said in a statement calling for a cease-fire.

Shifa Hospital director’s release

The decision to release Abu Selmia and 54 other Palestinian detainees back into Gaza appeared to be meant to free up space in overcrowded detention centers. Since the start of the war, Israeli forces have detained thousands of Palestinians from Gaza and the occupied West Bank. Many are being held without charge or trial in what is known as administrative detention.

“Our detainees have been subjected to all kinds of torture behind bars,” Abu Selmia told a news conference. “There was almost daily torture.”

He said guards used batons to beat detainees and terrorized them with dogs. He said some detainees had limbs amputated because of poor medical care. He said a beating caused his head to bleed and guards broke his finger.

The allegations could not be independently confirmed but matched other accounts of Palestinians who have been held in Israeli custody. There was no immediate response from the prison service, which has denied similar accusations.

Israeli forces raided Shifa Hospital in November, alleging that Hamas had created an elaborate command and control center inside. Abu Selmia and other staff denied the allegations and accused Israel of recklessly endangering thousands of patients and displaced people sheltering there. Abu Selmia was detained on Nov. 22.

After its first raid on Shifa Hospital, the military uncovered a tunnel beneath it leading to two empty rooms, as well as evidence that militants had brought wounded hostages to the facility. But the evidence fell short of showing an extensive base as claimed. Israel has since raided other Gaza hospitals on similar allegations, forcing them to shut down or dramatically reduce services.

Amid the uproar over Abu Selmia’s release, the various Israeli state organs responsible for detentions scrambled to shift blame.

Netanyahu’s office said Abu Selmia “belongs in prison” and that the prime minister had ordered a thorough review into how the release happened. It said the decision was made “without the knowledge of the political echelon or the heads of the organizations.”

Itamar Ben Gvir, Israel’s far-right national security minister who controls the country’s police and prison service, blamed the Defense Ministry.

Defense Minister Yoav Gallant’s office said prisoner releases are the responsibility of the prison service and the Shin Bet internal security agency. The prison service said the decision was made by the Shin Bet and the army, and released a document ordering his release that was signed by an army reserve general.

The Shin Bet said Abu Selmia had passed a risk assessment, “compared to other detainees.” It said the government had decided against its advice to release detainees determined to be less of a threat to free up space.

Israel launched its offensive after Hamas’ Oct. 7 attack, in which Palestinian militants killed some 1,200 people across southern Israel and took another 250 hostage. In its campaign, Israel has killed at least 37,900 Palestinians, according to Gaza’s Health Ministry, which does not say how many were civilians or fighters.

Associated Press writer Julia Frankel co-wrote this report from Jerusalem. Magdy reported from Cairo. Associated Press correspondent Edith M. Lederer at the United Nations contributed.