The Israel Defense Forces said Sunday it had "reached the seashore in the southern part of the city of Gaza and encircled the city of Gaza," calling the encirclement a "significant step" in the fight against Hamas.

"We will continue to attack strongly and continue to intensify our ground operation in the northern Gaza Strip and Greater Gaza City," the IDF said.

The IDF is still urging residents in northern Gaza to move south.

"We are intensifying our attack and this is already happening tonight significantly," the IDF warned.

Israeli Prime Minister Benjamin Netanyahu said Sunday at the Ramon Air Force Base in Israel that "there will be no cease-fire without the return of the hostages."

Israeli officials say 241 people have been taken hostage.

Secretary of State Antony Blinken traveled to Iraq to meet with Iraqi Prime Minister Mohammed Shia al-Sudani on Sunday following the secretary's visits to Israel, Jordan and the West Bank.

Blinken told reporters that his meeting with the Iraqi prime minister was productive and said he emphasized the need to prevent spillover from the conflict in Gaza.

"I made very clear that the attacks, the threats coming from militia that are aligned with Iran are totally unacceptable," Blinken said. "We're not looking for conflict with Iran. We've made that very clear. But we'll do what's necessary to protect our personnel."

"We're working very hard to make sure that the conflict in Gaza does not escalate, does not spread to other places, whether it's here, whether it's elsewhere in the region," he said.

Blinken was asked about Arab leaders' instance that nothing short of a total cease-fire would be acceptable.

"I think everyone would welcome humanitarian pauses -- there's no doubt about that," Blinken responded.

He said pauses "advance things that we're all trying to accomplish," including getting more humanitarian aid into Gaza, getting people out of Gaza and getting hostages home.

On his meeting with Palestinian Authority President Mahmoud Abbas, Blinken said the PA was "playing a very important role right now in the West Bank in trying to keep stability there."

-ABC News' Shannon Crawford

U.S. Secretary of State Antony Blinken visited the West Bank on Sunday, meeting Palestinian Authority President Mahmoud Abbas in an unannounced stop, the State Department said.

The two "discussed efforts to restore calm and stability in the West Bank, including the need to stop extremist violence against Palestinians and hold those accountable responsible," spokesperson Matthew Miller said in a statement.

At least three premature babies have died at the Al-Shifa Hospital in the Gaza Strip when a missile struck nearby and shut down the medical facility's backup generator, according to a doctor working at the hospital.

Dr. Ahmed Mokhallalti, the chief plastic surgeon at the hospital, told ABC News that the babies died when the power to their incubators was cut off Friday night into Saturday morning.

Mokhallalti said all of the hospital's ventilators were back up and running Sunday, but he expressed fear that more people would die at the hospital due to the relentless bombing.

Hospital officials said two patients in the hospital's intensive care unit also died on Sunday due to complications caused by the shelling.

The international humanitarian group Doctors Without Borders has made repeated calls for the shelling of hospitals in Gaza to cease.

"We are nearly sure that we are alone now. No one hears us," Dr. Mohammed Obeid of Doctors Without Borders said in a video statement from the Al-Shifa Hospital on Saturday.

Obeid said there are about 600 patients at the hospital who need medical care and need to be evacuated.

"The problem is [we need] to be sure we can evacuate the neonatal patients because we have 37 to 40 premature babies," Obeid said. "We have about 17 other patients in the ICU, and we have 600 postoperative patients who need medical care. So the situation is very bad. We need help."

-ABC News' Zoe Magee, Matt Gutman and Sami Zayara