The Israeli militaryhas ordered residents of Gaza City to evacuate to a designated "humanitarian zone" as its forces press deeper into the city, intensifyinga major offensiveaimed at seizing control of the area. The announcement came afterPresident Donald Trump saidFriday that the U.S. was in "very deep" negotiations with Hamas, who had earlier released a video showing two Israeli hostages seized from a music festival duringthe Oct. 7, 2023 terrorist attacks. Addressing residents on X Saturday,Israel Defense Forcesspokesperson Avichay Adraee urged civilians to move from Gaza City in the north to the Al-Mawasi safe zone, a coastal area in the southern city of Khan Younis. There, he said, they would find "food supplies, tents, medicines, and medical materials." In a separate post, he pressed "residents of Gaza" to leave early "and join the thousands who have already relocated there in the past days and weeks." The IDF have been carrying out heavy strikes on Gaza City for weeks, advancing through northern suburbs to within a few miles of its center. On Friday its forcesdestroyed a high-risetower in a densely populated part of the city. The IDF said it warned civilians beforehand and — without providing evidence — that it was being used by Hamas. Footage showed Palestinians running for safety as the building collapsed within seconds of it being hit. The Mushtaha Tower's management said it was being used for displaced people and denied it had been used for anything other than civilian purposes. The assault on Gaza City — declared a "dangerous combat zone" by Israel — is expected to displace hundreds of thousands of people, most of them already uprooted multiple times during the war. Aid groups warn the offensive could deepen the humanitarian catastrophe in the enclave and has already drawn international condemnation. The world'sleading body on hunger declared faminein Gaza for the first time last month. Israeli has denied reports of growing starvation in the enclave. Israeli Defense Minister Israel Katzsaid Friday that "the lock has been lifted from the gates of hell in Gaza," adding: "When the door opens, it will not close." His comments came after an Israeli military spokesman said Thursday that it now controls about 40% of the city, where about one million people lived prior to the war. The military controls about 75% of Gaza. Israel launched its military campaign after the Hamas-led terror attacks on Oct. 7, 2023, which saw 1,200 people killed and around 250 people taken hostage. Since then, Palestinian health officials say, more than 64,000 people have been killed in Gaza, including thousands of children, while much of the enclave has been reduced to rubble. Prime Minister Benjamin Netanyahu has described Gaza City as Hamas's last bastion, and ordered the military to seize the enclave's largest urban hub. He has also pushed for an all-or-nothing deal that would see all of the hostages released at once and Hamas surrendering. Hamas released a video Friday of two Israeli hostages taken on Oct 7. 2023, and one said he was being held in Gaza City. Guy Gilboa-Dalal and Alon Ohel are two of 48 people still being held by Hamas in Gaza,with 20 thought to be still alive. Gilboa-Dalal, looking exhausted, spoke for about three-and-a-half minutes, saying he was being held in Gaza City with other captives and feared being killed in Israel's assault. Some of the footage was taken in a car in a video dated August 28. NBC News could not independently verify when it was recorded. Ohel is also seen briefly in the footage. Elsewhere Trump told reporters Friday that Washington was in "very deep" negotiations with Hamas, but that the situation would become "tough" and "nasty" if Hamas did not release all the hostages. "We said let them all out, right now let them all out. And much better things will happen for them but if you don't let them all out, it's going to be a tough situation, it's going to be nasty," Trump said, adding that Hamas was "asking for some things that are fine," without elaborating.