According to Israel's military, a "rescue operation" was carried out in the city of Khan Yunis in southern Gaza on Tuesday night, when the bodies were found and later taken back to Israel. Five of them had previously been confirmed as dead, and the sixth person's death was confirmed by authorities on Tuesday.
The bodies were found in a tunnel in the city, and authorities estimate that one person may have died as early as March, reports the Israeli newspaper Haaretz.
Israel's Prime Minister Benjamin Netanyahu says that the country will continue to do "everything they can to bring back the hostages – both the living and the dead", according to the newspaper.
A relative of one of the dead hostages says to the Israeli radio channel Radio 103FM that the Israeli government has blood on its hands.
For (Prime Minister Benjamin) Netanyahu's survival, my uncle died. Get out all the living hostages now, he says to the channel.
Around 250 people were taken hostage by terrorist-stamped Hamas during their attack on Israel in October last year. Of these, about 100 are estimated to still be in Gaza after approximately the same number were released and a few more were rescued. Many of those who are still left are feared to no longer be alive.