Israel said it recovered the bodies of six hostages from a tunnel in Gaza where they were apparently killed shortly before its troops reached them, triggering protests by Israelis on Sunday and planned labor strikes over the failure to save them.
The Israeli military announced the recovery of the bodies from underground in the southern city of Rafah.
The bodies of Carmel Gat, Hersh Goldberg-Polin, Eden Yerushalmi, Alexander Lobanov, Almog Sarusi and Ori Danino have been returned to Israel, military spokesperson Rear Admiral Daniel Hagari told reporters.
A forensic examination determined that they had been "murdered by Hamas terrorists in a number of shots at close range" 48-72 hours previously, an Israeli health ministry spokesperson said.
Prime Minister Benjamin Netanyahu, who faces growing calls to end nearly 11 months of war between Israel and Hamas in Gaza with a deal that includes a ceasefire and the release of remaining hostages, said Israel would not rest until it caught those responsible.
"Whoever murders hostages - does not want a deal," he said.
Senior Hamas officials said that Israel, in its refusal to sign a ceasefire agreement, was to blame for the deaths.
"Netanyahu is responsible for the killing of Israeli prisoners," senior Hamas official Sami Abu Zuhri told Reuters. "The Israelis should choose between Netanyahu and the deal."
Thousands of Israelis joined protests in Jerusalem and Tel Aviv as pressure mounted on Netanyahu to do more to bring the remaining hostages home from Gaza.
The head of Israel's trades union federation, Arnon Bar-David, called for a general strike on Monday to pressure the government into signing a deal, and said Ben Gurion airport, Israel's main air transport hub, would be closed from 8 a.m. (0500 GMT).
"A deal is more important than anything else," he said. Defense Minister Yoav Gallant, who has clashed frequently with Netanyahu, also called for a deal and opposition leader and former Prime Minister Yair Lapid urged people to join the demonstration in Tel Aviv.
In Jerusalem, protesters blocked roads and demonstrated outside the prime minister's residence. Some lined roads, waving Israeli flags in honor of the six hostages.
Municipal services in Tel Aviv and other sites across Israel planned a half-day strike on Monday in solidarity with hostages and their families.
The recovered bodies were from about 250 hostages captured during the Hamas-led shock incursion into southern Israel on Oct. 7 that sparked Israel's retaliatory war in Gaza.
Their deaths leave 101 Israeli and foreign captives still in Gaza, but around a third of these are known to have died, with the fate of others unknown.
The Hostage Families Forum called on Netanyahu to take responsibility and explain what was holding up an agreement.
"They were all murdered in the last few days, after surviving almost 11 months of abuse, torture, and starvation in Hamas captivity. The delay in signing the deal has led to their deaths and those of many other hostages," it said.
'DEVASTATED AND OUTRAGED'
Netanyahu's office said he had spoken to the family of Alexander Lobanov, whose body was among those recovered, apologizing and expressing "deep sorrow".
But the family of another hostage, Carmel Gat, said they had refused to speak to Netanyahu, and instead called on Israelis to join the protests.
US President Joe Biden, who has closely followed the fate of the hostages, said he was "devastated and outraged" at the news of the death of 23-year-old Israeli American Goldberg-Polin and the other hostages.
"Hamas leaders will pay for these crimes. And we will keep working around the clock for a deal to secure the release of the remaining hostages," he said in a statement.
British Prime Minister Keir Starmer said he was "completely shocked" by the deaths.
Biden, speaking to reporters in Rehoboth Beach, Delaware, earlier, said he was "still optimistic" about a ceasefire deal.
Months of stop-start negotiations mediated by the United States, Qatar and Egypt have so far failed to secure a deal, despite increased US pressure and repeated trips by top officials to the region.
