U.S. and Israeli officials fear that most of the Israeli hostages held by Hamas since Oct. 7 have been killed, the Wall Street Journal reported Wednesday.

While the Israeli Army confirmed them deaths 34 of the 129 remaining hostages abducted by Hamas on October 7, citing information and findings obtained by troops operating in Gaza, the report said that “Israeli and US officials privately estimate that the death toll may be much higher.”

Some US estimates show that most of the hostages are already dead, US officials told the newspaper, stressing that US information about the hostages is limited and depends in part on Israeli intelligence.

American officials in particular reported that some of the hostages likely were killed by Israeli strikes in Gaza amid the ongoing war, while others had died from health problems, including injuries sustained during their abduction.

They also believe that hostages who are still alive are being used as human shields around the Hamas leadership, hidden deep in the Gaza tunnels, the Wall Street Journal reports.