Their family was notified by Belgian and Dutch authorities.
The brother and sister from New York who were reported missing after the Brussels attacks have now been confirmed as among the dead.
Read: Teen Missionary Who Survived Brussels Attack Speaks From Hospital: 'I Feel Lucky'
Alexander and Sascha Pinczowski's family said in a statement that Belgian authorities and the Dutch Embassy contacted them after the siblings' remains were positively identified.
"We are grateful to have closure on this tragic situation, and are thankful for the thoughts and prayers from all," the statement continued.
Before their deaths, Alexander, 29, and Sascha, 26, who were Dutch citizens living in New York, were on the phone with their mother, who heard the explosion shortly before they were disconnected, according to reports.
The siblings were returning to America after visiting relatives in the Netherlands.
Word of their passing came as U.S. Secretary of State John Kerry visited Brussels on Friday, days after the attacks that killed 34 people and wounded hundreds more.
Kerry said in a news conference on Friday morning in Brussels: “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.”
Read: Brussels Bombers Are The Latest in Long Line of Terrorist Siblings
He added: “The United States stands firmly with Belgium and with the nations of Europe in the face of this tragedy. We will continue to provide any assistance necessary in investigating these heinous acts of terrorism and bringing those responsible to justice.”
Watch: How You Can Be Prepared if a Terrorist Attack Occurs During Your Commute
