Dozens of people were killed or wounded in an Israeli airstrike that allegedly targeted a school housing displaced families in the city of Khan Yunis in the southern Gaza Strip on Tuesday morning, according to local medical staff.

A spokesperson for Nasser Hospital in Khan Yunis told ABC News that it had received scores of patients from the scene, including 30 who had died and dozens who were injured.

There was no immediate comment from the Israel Defense Forces.

The strike came on the heels of the IDF's announcement that it would be expanding its offensive on Gaza's militant rulers, Hamas, across the entire strip. The IDF alleges that Hamas uses civilian infrastructure in Gaza, including schools, for military activities -- claims which Hamas denies.

-ABC News' Nasser Atta and Morgan Winsor

The World Health Organization painted a bleak picture of the situation in Gaza on Monday night and called for Israel "to take every possible measure to protect civilians and civilian infrastructure, including hospitals, as per the laws of war."

According to the latest information from the WHO, there are only 18 functioning hospitals in Gaza, with three only providing first aid and the remainder just partial services.

The WHO warned thousands are likely to be cut off from health care services due to increased ground operations by Israel in southern Gaza. The open hospitals are operating beyond capacity, with the bed occupancy rate at 171% and intensive care units at 221%, the WHO said, based on data from the Hamas-run Ministry of Health.
WHO workers called the situation at the Nasser Medical Complex in Khan Younis "catastrophic, with the building and hospital grounds grossly overcrowded with patients and displaced people seeking shelter."

The WHO said in a statement Monday night it has recorded 203 "attacks on hospitals, ambulances, medical supplies, and the detention of health-care workers attacks on hospitals, ambulances medical supplies" between Oct. 7 and Nov. 28.

"This is unacceptable," the WHO's statement read. "There are means to protect civilians and civilian infrastructure, and they should be instituted."

-ABC News' Jolie Lash and Jade Coburn

Israeli ground forces are now operating "in and around" the key southern Gaza city of Khan Younis, an Israeli military official confirmed to ABC News.

The official said the IDF's "intention" was to "encircle" the city and "eradicate Hamas strongholds within it."

-ABC News' Tom Soufi Burridge

National security adviser Jake Sullivan said the U.S. is still having "intensive discussions" with "Israel, Qatar and Egypt about how to best get traction on a strategy that will get all the hostages out."

“The President and I, along with Secretary [of State Antony] Blinken and [CIA] Director [William] Burns, will stay in touch with our Israeli and Qatari counterparts, as well as our Egyptian counterparts, to press Hamas on this issue," Sullivan said. "Right now, Hamas is refusing to release civilian women who should have been part of the agreement. And it is that refusal by Hamas that has caused the end of the hostage agreement, and therefore, the end of the pause in hostilities."

Over 100 people remain hostage in Gaza. National Security Council spokesman John Kirby said Sunday the U.S. thinks "about eight" Americans remain hostage.

"Of course, for the United States, the paramount priority is getting the American hostages out and we are talking to the president about all of his options in terms of securing the release of American hostages," Sullivan said. "Beyond that, I'm not going to comment because we need to be able to have those sensitive, diplomatic discussions behind closed doors."

-ABC News' Molly Nagle