With 10 Americans still unaccounted for more than two weeks after Hamas’ massacre in Israel, U.S. Secretary of State Antony Blinken on Sunday said the terrorist group is believed to be holding at least some of them hostage in Gaza.

Blinken addressed the missing Americans during an appearance on NBC's "Meet the Press," saying that the U.S. is still uncertain whether some of the unaccounted for are dead, with their bodies yet to be recovered, though a "significant number" are believed to be held hostage. 

"We've got 10 unaccounted for Americans," Blinken said. "We believe that some significant number are hostages."

He continued, reiterating that "we have a pretty strong idea that some number of the 10 at least are being held in Gaza by Hamas."

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U.S. Secretary of State Antony Blinken

Secretary of State Antony Blinken on Sunday said the U.S. has "a pretty strong idea" that some of the 10 unaccounted for Americans are being held hostage by Hamas in Gaza. (AP Photo/Jacquelyn Martin, Pool)

More than 1,400 people in Israel have been killed in the war – mostly civilians slain during the Hamas attack on Oct. 7. Hamas is also believed to have taken more than 200 people hostage during its deadly incursion, which Blinken described as a slaughter.

"But, you know, what's happening is – and it just underscores the horror – Israel continues to discover, uncover people, who were killed, who were slaughtered, and I use that term very advisedly, slaughtered, on Oct. 7," he said.

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Two American nationals held captive by Hamas were released Friday. They were identified as Judith Raanan and her 17-year-old daughter Natalie Raanan, who originally were taken by Hamas from the Nahal Oz kibbutz in southern Israel near the Gaza Strip.

Video of President Biden speaking with both the mother and daughter by phone was posted to social media on Saturday.

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"We’re going to get them all out, God willing," Biden said in the video.