Israeli forces, advancing deep into western Khan Younis in Gaza’s bloodiest fighting of the new year so far, stormed one hospital and placed another under siege on Monday, cutting the wounded off from trauma care, Palestinian officials said.

Troops advanced for the first time into the al-Mawasi district near the Mediterranean Coast, west of Khan Younis, the main city in southern Gaza. There, they stormed the Al-Khair hospital and were arresting medical staff, Gaza health ministry spokesman Ashraf al Qidra told Reuters.

There was no immediate word from Israel on the situation at the hospital. The military spokesperson’s office had no comment.

The Palestinian Red Crescent said tanks had also surrounded another Khan Younis hospital, al-Amal, headquarters of the rescue agency, which had lost contact with its staff there. Qidra said at least 50 people were killed overnight in Khan Younis, while the sieges of medical facilities meant dozens of dead and wounded were beyond the reach of rescuers.

“The Israeli occupation is preventing ambulance vehicles from moving to recover bodies of martyrs and the wounded from western Khan Younis,” he said.

The Israeli military spokesperson’s office had no immediate comment on the situation at Al-Khair hospital.

Israel says Hamas fighters operate from in and around hospitals, which Hamas and medical staff deny.

“Hamas embeds its operation within and under hospitals and other medical facilities,” said Elad Goren of COGAT, the Israeli defence ministry branch that coordinates with the Palestinians. “A particular effort led by a dedicated team has been put on making sure that civilians have access to medical care.”

Residents said bombardment from air, land and sea was the most intense in southern Gaza since the war began in October, as Israeli tanks surged across Khan Younis from the east towards the Mediterranean coast.

Video filmed from afar showed scattered civilians wandering a ghost city, crowded with tents with abandoned laundry flapping on lines, as gunfire rattled and columns of smoke rose into the sky.

Israel launched an offensive last week to capture Khan Younis, which it now says is the principal headquarters of the Hamas militants responsible for the October 7 attacks on southern Israel that killed 1,200 people, according to Israeli tallies.