Israel-Gaza updates: IDF says it exposed Hamas tunnel under Shifa Hospital

At Gaza's Al-Shifa Hospital, 43 out of the 63 intensive care patients have died as oxygen in the intensive care unit runs out, according to Dr. Ahmed Mokhallalati, head of the hospital's plastic surgery department.

Mokhallalati told ABC News the mission of burying bodies is ongoing as more people die inside and outside the hospital.

Mokhallalati said he could still hear the Israeli tanks at the hospital gates Wednesday night.

Twenty-two of Gaza's 36 hospitals are now "non-functional," the World Health Organization said Wednesday.

The "14 hospitals remaining open have barely enough supplies to sustain critical and lifesaving surgeries and provide inpatient care," the WHO warned.

The organization in a statement reiterated its calls for a cease-fire, protection of civilians and "respect for international humanitarian law."

The Israel Defense Forces said its operation at Gaza's Al-Shifa Hospital complex is ongoing.

The IDF said its forces "engaged with" and killed "a number of terrorists" when entering the hospital complex.

Following searches in the hospital, the IDF said its troops "located a room with technological assets, along with military and combat equipment used by the Hamas terrorist organization."

Palestinian journalist Khadr al Zanoon, who is at the hospital, told ABC News no fighting has taken place inside, but he can hear tanks outside.

He said Hamas fighters are not in the hospital but are in the area around it and are fighting with Israeli forces.

He said Israeli forces have detained some Palestinians who were inside the hospital.

2:49

Families of hostages march to Jerusalem, demanding their release

Israeli sources hint a possible hostage deal could come within days as families march to Jerusalem demanding their release.

ABCNews.com

The raid on Al-Shifa Hospital began early Wednesday around 3 a.m. local time, after Israeli forces had moved closer to the medical complex for several days.

Thousands of civilians, along with hundreds of patients -- most of whom are seriously ill -- have been sheltering at Al-Shifa, according to hospital staff and Gaza health officials.

The IDF alleges that Hamas has placed its command centers under Al-Shifa and other hospitals in Gaza and is deliberately sheltering behind Palestinian civilians -- claims that the militant group denies.

National Security Council spokesperson John Kirby on Wednesday denied that the U.S. gave any "OK" for the Israeli operation at Gaza's Al-Shifa Hospital.

"These are Israeli military operations that they plan and they execute on, you know, in accordance with their own established procedures, that the United States is not, was not, involved in," Kirby said.

He also denied that the U.S. confirming intelligence that Hamas uses the hospital as a control center had anything to do with the timing of the Israeli military operation at the hospital, which began only hours after Kirby's announcement.

Kirby also said Israel's hospital operation was "not a focus" of President Joe Biden's Tuesday night conversation with Israeli Prime Minister Benjamin Netanyahu and would not say if the U.S. got a heads up about the operation.

"Again, we don't expect the Israelis to advise us or inform us when they are going to conduct operations," Kirby said. "We talked to them routinely every day, and certainly we talked to them about our continued concerns over civilian casualties and sharing our perspectives on the best way to minimize, but these are their operations."

-ABC News' Sarah Kolinovsky