One Israeli hostage was killed by his guard and two women captives were seriously wounded in two separate incidents in Gaza, the spokesperson for Hamas’ armed al-Qassam Brigades, Abu Ubaida, said on Monday.

Abu Ubaida blamed the incident on what he described as Israeli “massacres” against Palestinians.

“The enemy government [Israel] bears full responsibility for these massacres and the resulting reactions that affect the lives of Zionist prisoners,” Abu Ubaida said in a statement posted on Telegram.

He said a committee has been formed to investigate the details and the findings will be announced later, adding that efforts are underway to save the two wounded hostages.

It is the first time that Al-Qassam has said its guards killed hostages. The group has often attributed previous killings of hostages to Israeli bombardment in the strip.

Israeli Army spokesperson Avichay Adraee said in Arabic on X: “In the last few minutes, the terrorist Hamas published a written report claiming that in two separate incidents, Hamas activists killed an Israeli captive and wounded two women captives. At this stage there is no intelligence document to confirm or refute Hamas’ allegations. We continue to investigate the credibility of the statement and will provide information where we have it.”

The development comes shortly after the Palestinian group named Gaza leader Yahya Sinwar, one of the masterminds behind the October 7 attack on Israel, as its new leader following the assassination of former leader Ismail Haniyeh in Tehran on July 31.

On Saturday, an Israeli airstrike on a Gaza City school compound housing displaced Palestinian families killed around 100 people.

Israel on Monday said 31 militants were among the dead. Hamas and the Islamic Jihad denied the Israeli allegations, and said that no gunmen were present at the school.

The incident comes amid conflicting reports about expectations regarding the outcomes of talks aiming to end the war in Gaza slated for Thursday. Hamas on Sunday cast doubt on its participation in the anticipated talks.