Family and friends are using social media in an attempt to find siblings who have been missing since a suicide bomber detonated two bombs Tuesday at Brussels Airport.

Sascha and Alexander Pinczowski called family Tuesday to say they had safely made it to Brussels Airport ahead of a scheduled flight back to America. During the call, "the family heard an explosion and glass shattering. Then the line went dead," Dutch news site 1Limburg reported.

They have not been heard from since.

"Their mother is worried sick," Mafalda De Andrade Vasconcelos wrote in a Facebook plea for information. "If you have friends that work in hospitals or emergency centers, please share with them so that if they recognize them they may get the police to contact the parents."

The Pinczowski siblings live in New York, WCBS reported. According to 1Limburg, their father is from Maastricht, Netherlands.

Dutch Minister of Foreign Affairs Bert Koenders called the disappearance "a terrible situation" in an interview with public broadcaster NOS. He vowed the embassy would do all it could to work with Belgian authorities and track down the siblings.

Belgian authorities said at least 31 people died when suicide bombers struck Tuesday at Brussels Airport and the Maelbeek Metro station. About 270 other people were injured.

Investigators have identified the suicide bombers as a pair of brothers, Khalid and Ibrahim El Bakraoui. At least one suspect remained at large Wednesday.