The army’s chief spokesman, Rear Admiral Daniel Hagari, said Israeli troops found the hostages and erroneously identified them as a threat. He said it was not clear if they had escaped their captors or been abandoned.
"Unfortunately, the tragic results of this event ended in their deaths," Hagari added at a media briefing.
"The IDF began reviewing the incident immediately... Immediate lessons from the event have been learned, which have been passed on to all IDF troops in the field," it added, expressing "deep remorse over the tragic incident," the army said in a statement.
The White House said the incident was a "tragic mistake" and "heartbreaking" news.
"I don't believe it's possible to draw broader conclusions from this particular event and what it says about (the Israeli armed forces') ability to be more surgical and more precise." in their actions, White House spokesperson John Kirby commented Friday.
The army identified two of the hostages as Yotam Haim, who was taken from Kibbutz Kfar Aza during Hamas's October 7 attack, and Samer El-Talalqa, taken from Kibbutz Nir Am.
It said it was withholding the third hostage's name at the family's request.
Hamas kidnapped around 250 hostages during its October 7 attack on southern Israel, which killed 1,139 people, according to official figures.
Israel's retaliatory war against the group has killed more than 18,700 people, according to the territory's Hamas-run health ministry.
The Israeli government has repeatedly stated that bringing home all of the hostages is one of its chief war aims.
U.S. President Joe Biden on Thursday urged Israel to "be more careful" when going after Hamas in Gaza, and focus on saving civilian lives.
At an event at in the U.S. state of Maryland, Biden was asked by reporters if he wants Israel to scale back its assault of Gaza by the end of the year.
"I want them to be focused on how to save civilian lives; not stop going after Hamas, but be more careful," Biden responded.
Israel's defense minister said Thursday it will take months to destroy Hamas, predicting a drawn-out war even as his country and its top ally, the United States, face increasing international isolation and alarm over the devastation from the campaign in Gaza.
Some information in this report came from The Associated Press
Editor's Note: This story has been updated with comments from the White House
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