Hamas has threatened to execute the hostages it is holding at Gaza, it is being reported in Israel. The threat, which came following a number of Israeli air force strikes on targets inside the Hamas-run Gaza Strip, adds a new layer of anguish to the worst turmoil many Israelis have ever seen.

Israeli news organizations are reporting that a representative of Hamas’s Izz ad-Din al-Qassam Brigades told a Palestinian news service at Gaza, “From this hour, any targeting of our people in the safety of their homes, without warning, will be met with the execution of civilian hostages, which will be broadcast with video and audio.”

The threat appears at least in part to be a reaction by Hamas to the Israeli Defense Force’s change in tactics with respect to striking targets at Gaza. During previous conflicts, Israeli forces customarily dropped dummy bombs on roofs of buildings set to be targeted in order to give civilians time to flee. Now, while in the throes of battle, that practice, known colloquially as “knocking the roof,” has been put on hold, an Israeli defense official told members of the Knesset on Monday. 

The surprise weekend attack perpetrated by Hamas killed more than 700 people in Israel, including at least 260 at a crowded music festival that became the scene of one of the country’s worst civilian massacres. Israeli officials put the total number of hostages taken by Hamas in the combined assaults at about 150. 

The hostages include women, children, and the elderly. The figure includes an unknown number of festival participants who were abducted as well as nationals from other countries in addition to Israel. 

The capture of dozens of Israelis posed an immediate challenge for Prime Minister Netanyahu. Now, the fresh threat from Hamas, which came on the same day that Israel announced a “full siege” of the densely populated Gaza Strip, will complicate the crisis. 

The issuance of the warning also appears to be at odds with some reports that Qatar has been attempting to negotiate a prisoner exchange. Reuters reported that Qatari mediators said they held calls with Hamas officials to try to negotiate the release of the Israeli women and children seized by the terrorists and held in Gaza in exchange for the release of 36 Palestinian women and children from Israel’s prisons, but an Israeli official denied that report.