Fighting raged Monday in and around the besieged Gaza Strip's largest hospital complex where Israel said its forces killed and arrested Hamas militants, as Palestinians fled by foot under heavy bombardment. While the army launched the overnight raid at Gaza City's Al-Shifa hospital, the Israeli government sent the head of its Mossad spy agency to Qatar for renewed talks toward a ceasefire and hostage release deal. The devastating war since October 7 has left roughly half of Gazans — around 1.1 mn people — experiencing "catastrophic" hunger, a UN-backed food security assessment warned. The expert report is "exhibit A for the need for an immediate humanitarian ceasefire", said UN Secretary-General Antonio Guterres, decrying an "entirely man-made disaster". Gaza's soaring civilian death toll and large-scale destruction have hardened global opposition to Israel's military operation and siege, including accusations of deliberate starvation of Palestinian civilians. Israel has carried out a relentless bombing campaign and ground offensive that Gaza's health ministry says has killed at least 31,726 people, most of them women and children. In the latest heavy battle, Israeli forces raided Al-Shifa in an operation the army said targeted senior Hamas militants. Witnesses reported air strikes and tanks near the complex crowded with thousands of Palestinian patients and displaced people. The health ministry in the Hamas-run Gaza Strip said nearby residents had reported dozens of casualties who could not be helped "due to the intensity of gunfire and artillery shelling". The army identified one of the fatalities as Hamas internal security official Fayq al-Mabhouh. A Gaza police source confirmed his death and said he was a brigadier general in the force. Israeli forces previously raided Al-Shifa in November, when ground operations were focused on northern Gaza. World Health Organization chief Tedros Adhanom Ghebreyesus said he was "terribly worried" about the renewed fighting around Al-Shifa which was "endangering health workers, patients and civilians". Global concern has focussed on Gaza's far-southern city of Rafah, where about 1.5mn Palestinians now live, many of them in crowded shelters and tent cities near the Egyptian border. Repeated Israeli warnings of a looming ground invasion have raised fears of an even worse humanitarian catastrophe.