A senior Hamas official is warning that Israel’s decision to resume the war against the terror group after ceasefire talks stalled is a "death sentence" for the remaining hostages, according to The Associated Press.

That could include the last living American hostage, Edan Alexander, who was born in Tel Aviv and raised in New Jersey. A group of hostage family members expressed outrage at Israel's decision.

The Hostages and Missing Families Forum said Israel "chose to give up on the hostages" by resuming the war. The organization called for protests on Tuesday following the airstrikes, saying that "military pressure could further endanger their lives and complicate efforts to bring them home safely."

There are still 59 hostages in Gaza, but Israel believes only 24 of those who remain are alive. The ceasefire was meant to be carried out in two phases. However, talks on phase two, which would have meant an end to the war and the release of the remaining hostages, have stalled.

CEASEFIRE OVER AS ISRAEL STRIKES GAZA AFTER HAMAS REFUSED TO RELEASE HOSTAGES, OFFICIALS SAY

The Israeli airstrikes left more than 400 Palestinians, including women and children, dead, according to the Hamas-run Gaza Health Ministry. Fox News cannot independently confirm the death toll put out by the ministry controlled by a terror organization.

"The ER was just chaos, patients everywhere, on the floor," Dr. Tanya Haj Hassan, a volunteer with Medical Aid for Palestinians based at Nasser Hospital, told the AP. She apparently treated multiple patients who died in the emergency room.

This marks the end of a nearly two-month-long ceasefire, which saw the release of multiple hostages. The Israel Defense Forces (IDF) announced on Twitter that the Jewish state was carrying out "extensive strikes on terror targets" in Gaza.

The IDF said on Tuesday that its targets belonged to both Hamas and Palestinian Islamic Jihad, and included launch posts, weapons stockpiles and military infrastructure.

Egypt reportedly called on all parties to show restraint and work towards a long-term ceasefire, according to Reuters.

HAMAS SAYS AMERICAN-ISRAELI HOSTAGE WILL ONLY BE FREED IF CEASEFIRE IS IMPLEMENTED

Israeli Prime Minister Benjamin Netanyahu met with security officials at the Kirya, Israel’s version of the Pentagon, on Tuesday following the airstrikes. 

"Israel will, from now on, act against Hamas with increasing military strength," according to Netanyahu’s office wrote in a series of posts on X as the airstrikes commenced.

Palestinians were ordered by Israel to evacuate eastern Gaza, signaling the IDF could resume its ground operations in the Strip, according to The Associated Press.

United Nations High Commissioner for Human Rights Volker Turk's office called the airstrikes "horrifying," saying "this nightmare must end immediately."

"It is time for the countries of the world to take seriously our unwavering commitment to return all our hostages home and defeat the enemy," Israeli U.N. Ambassador Danny Danon said in a statement. "Let me be clear: Nothing will stop us from fighting to free our hostages who have been held in brutal Hamas captivity for 527 days."

Fox News' Trey Yingst, Louis Casiano, Landon Mion and The Associated Press contributed to this report.