The U.S. believes there are eight or nine Americans still being held in Gaza, National Security Council spokesperson John Kirby said, adding that the U.S. does not have "solid information on each and every one of them."

Asked if Americans were expected to be released in the coming days, Kirby said the administration "certainly hope[s] so," but did not say more.

"I mean, we're going to watch this very, very closely. We're certainly hoping that another batch of hostages gets released today as part of the fourth and final day of the original agreement. We’re going to be watching closely to see if any Americans are in that group," Kirby said.

"We don't really know until you get into the end game who's going to be actually on that list and then, even then, you got to watch closely [to see] if who's on the list is folks that actually come out," he said.

Kirby was asked specifically about the two American women who were expected to be part of the first round of releases, and he reiterated his hope they would be released Monday.

-ABC News' Molly Nagle

Hamas officials said they've received a list of Palestinian prisoners who are expected to be released from Israel on Monday in exchange for hostages. The list includes three women and 30 children, Hamas officials said.

Muhammad Ibrahim Asfour was among the Gaza residents who returned home during the cease-fire to find destruction where homes used to be.

"I was shocked, and when I saw the house I started crying," Asfour told ABC News. "There were 50 people in the building here -- all of my brothers and father were living here."

"The situation here is more difficult than you can imagine," Abdelkader Darma told ABC News. "When I came home I was shocked."

"People do not know where to go," Darma said. "I and six other people slept on two mattresses and two pillows, which means you do not know how to sleep. They sleep three against three, and you find his feet in front of your face."

“I hope the truce will be extended and a solution will be found because it is enough. People are sleeping in the street," Darma said. "How can you bear it?"

-ABC News' Zoe Magee and Sami Zayara

Majed Al-Ansari, spokesperson for Qatar's Ministry of Foreign Affairs, said an agreement has been reached to extend the humanitarian truce between Israel and Hamas for two more days.

Hamas said this truce is "under the same conditions as the previous truce."

Diaa Rashwan, chairman of Egypt's State Information Service, said earlier on Monday that the deal would involve the release of 10 Israeli women and children being held hostage by Hamas in exchange for 30 Palestinians detained in Israeli prisons each day of the extension.

After reaching an "impasse" in negotiations with Hamas, Prime Minister Benjamin Netanyahu ordered Israel's negotiation team to return from Doha, Qatar, Israeli officials said.

"The terrorist organization Hamas did not fulfil its part of the agreement, which included the release of all children and women according to a list that was forwarded to Hamas and approved by it. The head of the Mossad thanks the head of the CIA, the Egyptian Minister of Intelligence and the Prime Minister of Qatar for their partnership in the tremendous mediation efforts that led to the release of 84 children and women from the Gaza Strip in addition to 24 foreign citizens," according to a statement issued on behalf of Israel's Intelligence and Special Tasks Agency.

-ABC News' Edward Szekeres