A suspected Hamas terrorist appeared with a knife Thursday at the grounds of the music festival in southern Israel where hundreds of concertgoers were killed by Hamas this weekend.

Israeli soldiers immediately took down the suspect and took him into custody.

Secretary of State Antony Blinken on Thursday visited an Israel donation center, where he was greeted by applause and cries of “God bless America.”

Blinken dropped off his own contribution to benefit survivors who have lost everything.

He then spoke to Lior Gelbaum, a 24-year-old American-Israeli dual citizen, who was attending the music festival that was attacked by Hamas.

Through tears, she told Blinken that many of her friends were killed or taken hostage.

"Thank you for being here. It’s really important," she said. "And if there is any way to help -- first priority, first priority is our friends and family that are still in Gaza."

"We're thinking of them and trying to do everything we can. We want to bring them home," Blinken responded. "I admire your strength."

Another volunteer told Blinken he had just come from the fourth funeral of a friend who lost a child. The volunteer said all of the mourners had expressed that after concluding their mourning period, they would rebuild the country.

-ABC News' Shannon Crawford

New York City's Empire State Building will shine blue and white lights in honor of Israel from 10 p.m. local time Friday until sunrise on Saturday.

The Empire State Building's lights usually extinguish at 2 a.m. local time, but they will be extended in this case so people in Israel can see in real-time.

Emirates announced it will suspend flights to and from Tel Aviv through Oct. 20.

The airline also said customers with onward connections to Tel Aviv will not be accepted for travel at their point of origin until further notice.

-ABC News' Amanda Maile

Human Rights Watch has accused Israel of using white phosphorus munitions in military operations in Gaza on Wednesday, saying it violated international humanitarian law by putting civilians at unnecessary risk.

In a report released Thursday, Human Rights Watch said it based its determination on a video it said it has verified, as well as two eyewitness accounts.

The Israel Defense Forces said in a statement to ABC News that claims they used white phosphorus in Gaza are "unequivocally false."

ABC News geolocated a video showing a jellyfish-shaped plume of white smoke over the port of Gaza. The video was posted on Wednesday by the official Palestinian news agency WAFA and matches images posted on social media and by other news outlets on the day.

Two experts -- Amael Kotlarski, the weapons team manager for the defense intelligence firm Janes, and Amnesty International weapons investigator Brian Castner -- told ABC News that images suggested munitions deployed over the port of Gaza on Wednesday appeared to contain white phosphorus.

"We have verified that Israeli artillery forces striking Gaza are equipped with M825 and M825A1155mm white phosphorus projectiles," Castner told ABC News, pointing to photographs by an Anadolu Agency photographer taken on Monday and showing Israeli troops handling shells labeled "M825A1."

Kotlarski said visual evidence alone was not sufficient to confirm that these specific shells were used in the Gaza port strikes.

There are "perfectly legal" military uses for white phosphorus munitions, Kotlarski said, including to create a smoke screen to conceal movements, to mark targets for artillery or air strikes, or to illuminate a battlefield. However, its use in urban areas is "problematic due to the higher risk of collateral damage," Kotlarski said, including the munitions' potential to cause severe burns.

White House Principal Deputy Press Secretary Olivia Dalton said Friday the U.S. had not independently verified allegations Israel used white phosphorous "so that is not something I would want to speculate about or weigh in on at this time."

-ABC News' Christopher Looft, Ben Gittleson and Jordana Miller