This story was updated at 8:51 a.m. with additional information.
UPDATED: NEW YORK (AP) — Two New York City siblings are among the dead in the attacks in Brussels, their family said Friday.
Alexander and Sascha Pinczowski, Dutch nationals who lived in the U.S., were headed home to the states when a bomb exploded at the airport Tuesday. Alexander, 29, was on the phone with his mother in Holland when the line went dead, said James Cain, whose daughter Cameron was engaged to Alexander.
"We received confirmation this morning from Belgian authorities and the Dutch embassy of the positive identification of the remains of Alexander and Sascha from the terrorist bombing at the Brussels Airport," Cain said on behalf of the Pinczowski family. "We are grateful to have closure on this tragic situation, and are thankful for the thoughts and prayers from all. The family is in the process of making arrangements."
Alexander Pinczowski had traveled to Holland to work on a craft-related business that he and Cameron were going to start together, Cain said.
The couple met six years ago while taking summer courses in Durham, North Carolina. They hadn't set a wedding date but had planned to marry within the year, Cain said.
He called Alexander "intimidatingly smart, a brilliant young man."
Sascha Pinczowski, 26, was a 2015 graduate of Marymount Manhattan College in New York with a degree in business. She spent last summer as an intern at a catering company, Shiraz Events.
Shiraz Events President Shai Tertner called her "a bright, hardworking young woman, with a great career ahead of her."
Both siblings had hoped to obtain U.S. citizenship one day, said Cain, a retired ambassador to Denmark.
Mayor Bill de Blasio tweeted that New York had lost "two of our own" in the attacks.
"Two young siblings from our city were taken from us far too soon, and our hearts break for the family and friends of Sascha and Alexander," de Blasio said in a statement. "New York City has shown time and again that we will not succumb to the threat of terrorism, and we will not live in fear. Today we vow to continue standing up for freedom and democracy in honor of those we have lost."
Gov. Andrew Cuomo also extended his sympathies to the family.
"Their lives were cut short by cowards who have chosen extremism and hate instead of peace and unity. On behalf of all New Yorkers, I extend our deepest prayers and condolences to the Pinczowski family, as well as all those who lost loved ones in Tuesday's heartbreaking attacks," Cuomo said.
The bombings in Brussels at the airport and in the subway killed 31 people and injured nearly 300.
A U.S. official says at least two American citizens have been confirmed killed in this week's attacks in Brussels.
The announcement comes as Secretary of State John Kerry is visiting the city to express his condolences to the Belgian people.
Speaking after meeting with Belgian Prime Minister Charles Michel, Kerry said the "United States is praying and grieving with you for the loved ones of those cruelly taken from us, including Americans, and for the many who were injured in these despicable attacks."
He did not give a specific number but a senior official said the families of two Americans had been informed of their deaths in Tuesday's attacks. The official, who was not authorized to speak to the matter publicly and spoke on condition of anonymity, did not have further details.
Meanwhile, relatives of the couple from Tennessee and Kentucky said they were told earlier in the week that their family members had been located, but then were told shortly thereafter that the couple had not been located.
It is unclear what led to the mistake, and the whereabouts of the couple are still unknown.
At least four Americans were reported missing after the attacks, NBC news reported.
The family of two New York City siblings has confirmed that authorities confirmed they died in the terrorist bombings in Brussels.
Belgian authorities and the Dutch Embassy positively identified the remains of Alexander and Sascha Pinczowski.
The information was issued Friday by James Cain on behalf of the Pinczowski family. Cain is the father of Alexander's fiancé, Cameron Cain.
He says the family is "grateful to have closure on this tragic situation."
The siblings were on the phone with a relative at Brussels airport when the phone went dead.
They were Dutch nationals, according to officials in the Netherlands, but both apparently had lived in the U.S. for some time.
About a dozen Americans were confirmed to be injured in the attacks.
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LOUISVILLE, Ky. (AP) — A young couple originally from Tennessee and Kentucky have not been seen since they waved goodbye to the woman's mother at the international airport in Brussels, one of two sites in the city where terrorist bomb attacks killed at least 34 people.
Justin and Stephanie Shults were dropping Stephanie's mother, Carolyn Moore, off at the airport and were watching her walk through security when the bombs went off Tuesday, Stephanie's cousin, Larry Newsom, told The Associated Press on Wednesday.
Justin Shults was from Gatlinburg.
Carolyn Moore turned to wave goodbye and they waved back, then the bomb exploded and knocked Moore to the ground, Newsom said. She searched but could not find them in the chaos.
Moore has stayed in Brussels and Shults' father is on his way there to check hospitals, Newsom said.
"We hope they've just been helping people, which is very much their nature," he said. "But we can't believe they wouldn't have checked in. It's very concerning that we're a day out and we don't know where they are."
By late Wednesday, relatives were still awaiting news of the couple, and U.S. Sen. Bob Corker, R-Tenn., released a statement at the families' request.
"At this time, neither Belgium nor U.S. officials have confirmed that Justin and Stephanie Shultshave been located," the statement said. "We are thankful for the outpouring of love and support we have received at this difficult time and ask for prayers for Justin and Stephanie."
The Islamic State group has claimed responsibility for the attacks at the airport and a subway in Brussels that injured hundreds and left scores unaccounted for.
Justin's grandfather, Bobby Shults of Sevierville, Tennessee, said he has been watching news reports constantly, hoping for an update on the couple.
"We haven't been told anything," he said. "We would like to be told something. We'd just like to know what's happening."
Stephanie Shults is from Lexington, Kentucky, and Justin Shults is from Gatlinburg, Tennessee, according to their Facebook pages and local news media reports.
They both graduated in 2009 from Vanderbilt University's Owen Graduate School of Management with master of accountancy degrees, according to university spokesman Jim Patterson.
The couple had moved to Brussels in 2014, Newsom said. He said they were excited to live in Europe and traveled frequently.
"They really are very genuine, sweet kids," he said. "They've invited all kinds of people from our family to visit them. They say, 'Oh, come see us in Belgium, it's wonderful. You can take the train anywhere.' They're that generous. They wanted their family to come experience what they've experienced."
The Mars food and candy corporation identified Stephanie Shults as an employee in Belgium.
The company posted on its Facebook page that is has been unable to contact her and asked anyone with information on her whereabouts to get in touch.
"We are hoping for the best," the company wrote. "And our thoughts are with Stephanie's and Justin's families."
This story is developing.