The Israeli military has released footage which it says shows hostages being taken into Gaza's largest hospital after the deadly Hamas attacks of 7 October.
A military spokesman said one of them - a soldier - was murdered there.
Cpl Noa Marciano, 19, was killed after being taken into al-Shifa hospital with minor injuries, he said.
Israel said a tunnel had been found at the site which it claims was a Hamas command centre. Hamas denies that.
The OceanNewsUK has not been able to verify the video which was presented at a news briefing by the Israel Defense Forces (IDF) on Sunday.
"This morning we updated Noa's family that according to our findings, she was kidnapped to a safe house near Shifa," Rear Adm Daniel Hagari, IDF chief spokesperson told reporters.
"During IDF air strikes in the area, the Hamas terrorist who was holding Noa was killed and she was wounded in the air strike, but not a life-threatening injury. Noa was taken inside Shifa hospital, where she was murdered by another Hamas terrorist."
Hamas has previously claimed Ms Marciano was killed in an Israeli air strike, which the IDF said occurred on 9 November.
Rear Adm Hagari then played CCTV footage which he said was from the morning of 7 October - the day Hamas launched its surprise attack on southern Israel in which 1,200 Israelis were killed and more than 240 taken hostage.
The video showed two hostages being brought into the hospital, Gaza's largest and most modern.
Armed men can be seen in the CCTV video which is date-stamped 7 October. One of the hostages appears to be resisting - the other is shown on a stretcher.
The IDF has been under pressure to substantiate its claim that Hamas operated an expansive command centre underneath the vast medical complex in the north of the territory.
Responding to the video released by Israel, the Hamas-run health ministry in Gaza said it was not able to confirm the authenticity of the footage.
The ministry also said it was Israel which bore full responsibility for the deterioration and collapse of health services in Gaza.
Earlier, the IDF released a video that it said showed a tunnel 10m (33ft) below ground that runs for 55m up to a closed and reinforced door.
It said this was now part of the evidence that "clearly proves" numerous buildings in the hospital's complex have been "used by Hamas as cover for terrorist infrastructure and activities".
The latest video is not yet the evidence that's been promised of the sort of vast and intricate operation depicted in a computer simulation which the IDF previously released showing what it believes any Hamas base underground at al-Shifa could look like.
The US has said it also has intelligence that Hamas has used hospitals in the Gaza Strip, including al-Shifa, as command centres and weapons stores.
Israel has cited US intelligence to substantiate their claim of the existence of a major headquarters at the complex but the Americans' use of the term "node" may suggest a smaller operation.
Israel believes it is building a credible case and is keen to present evidence as and when it finds it.
While Israel's allies have supported its military campaign of retaliation, which it says is aimed at eliminating Hamas, they have expressed a lot of unease at the toll that the offensive is having on civilians.
The Hamas-run health ministry says the death toll in Gaza since then has reached 12,300. More than 2,000 people are feared to be buried under rubble.
The government of Israeli Prime Minister Benjamin Netanyahu is also under pressure from families of the hostages. They want him to do more to free those held by Hamas.
On Saturday, protesters calling on the Israeli government to prioritise securing the release of hostages walked from Tel Aviv to Jerusalem before holding a demonstration outside Mr Netanyahu's residence.
The prime minister, however, appears undeterred in his mission.
He says his first goal of the war is to destroy Hamas; the second to return the hostages; and the third to eliminate the threat from Gaza.
