At least 13 people were killed and 56 people were injured -- 21 of them critically – on Wednesday after a hit by "direct fire" struck the UNRWA Khan Yunis Training Center, where displaced people have been sheltering in Gaza, according to the UNRWA.

“There are 43,000 internally displaced people registered in this massively overcrowded UNRWA shelter, and all of them now find themselves at the epicentre of the war,” Thomas White, the director of UNRWA Affairs in Gaza, said in a statement. “Many have already been displaced multiple times and have nowhere else to go.”

CIA Director Bill Burns will travel to Europe soon to meet with Qatari, Egyptian and Israeli officials for talks on a potential agreement to free hostages held in Gaza in exchange for a prolonged cessation of hostilities, according to two U.S. officials.

This will be at least the third time Burns has journeyed abroad to push negotiations forward.

Various proposals have been discussed in recent weeks, and the two U.S. officials declined to speculate on the contours of any deal currently on the table. But the officials said the U.S. believes it is now possible to secure the release of all the remaining hostages through a single diplomatic agreement.

The officials said that securing the return of the remains of dead hostages would also be part of the negotiations.

As many as six American hostages -- five citizens and one lawful permanent resident -- are still believed to be alive in Gaza. The FBI has open cases on the deaths of at least two American hostages whose bodies are believed to still be in Gaza.

-ABC News’ Shannon Crawford

Hamas will abide by any cease-fire decision issued by the International Court of Justice, Hamas leader Osama Hamdan said Thursday.

The International Court of Justice is expected to issue a ruling Friday.

Hamdan also said Hamas will release the Israeli hostages being held in Gaza if the Israeli enemy releases its prisoners.

Sahar Amer is married with two children, ages 2 and 4, and lives in a camp in Khan Younis in southern Gaza.

"Since the beginning of the war, I have believed that this camp was safe -- a very densely populated area, and my relatives chose me as our home to seek refuge in to escape the bombing," Amer, 28, told ABC News.

"Everything has been difficult to obtain since the beginning of the war: food, water and treatment," Amer said. "But unfortunately, what happened a week ago changed everything. The area became unsafe due to the sudden entry of [Israeli] tanks behind Nasser Hospital, which is only several meters away from us."

"During the Israeli army’s incursion behind the hospital, we lived a very terrifying night due to intense artillery shelling," she said. "I could hear the sounds of bullets flying."

"Then the quadcopter planes started shooting at citizens. One time I was on the roof of the house with my children and we miraculously escaped death," Amer said.

"I did not expect the army to infiltrate in this way," she said, noting that her family "took refuge with us, believing that this area is safe and that the army cannot encircle the camp like this."

One night she headed home and said she found tanks "stationed west of the camp and surround[ing] the place."

"I felt very afraid that the tanks were approaching my house,” she said. “I was hugging my children.”

Amer wanted to leave her house, but couldn’t find a car. So she took her children and they fled on foot.

"When I approached the road, a tank appeared … and prevented us from passing through,” she said. "I returned home crying and afraid that our fate will be death like the residents of other areas. I sent a message to my mother and sister to pray for me to be saved."

"I went out with great difficulty the next day. I left my home crying. I do not want to be displaced -- I want to remain safe in my home." she said. "I hope the war will end -- there is enough death and destruction."

-ABC News’ Ruwaida Amer