The two are believed to have been on the phone with their family when the first bomb went off

By Char Adams
Updated March 23, 2016 08:45 AM

A brother and sister from New York are among those missing after Tuesday’s terror attacks on Brussels that killed at least 34 and left hundreds injured.

Friends of Sascha and Alexander Pinczowski said that the two were getting ready to fly back to New York Tuesday morning when the first bomb went off in the Brussels airport’s departures hall.

They took to social media to enlist the help of the public in finding their friends.

“Their mother is worried sick since she can’t get hold of them since this morning when they were checking in at Zaventem airport,” one friend wrote in a Facebook post, including photos of the pair.

A Dutch news outlet reported that the two called home to tell their family they had made it to the airport. The family said they heard an explosion and glass shattering before the line went dead.

Friends of the pair confirmed details of the phone call to PEOPLE. Friend Mark Lewis, who lives in the Netherlands, saying that his search for the pair has been unsuccessful.

“Alex is the sweetest person ever. After the explosion we haven’t heard from them,” he tells PEOPLE. “We tried all hospitals with no luck. Their mom was the last to speak to them, but their call was cut off after the explosion.”

Two explosions went off in the Brussels airport about 8 a.m. on Tuesday, killing 14 and injuring nearly 100 people. A second attack occurred at the Maalbeek Metro Station near the European Union’s headquarters about an hour later.

Officials said 20 were killed and at least 106 injured at the metro station. ISIS has claimed responsibility for the attacks, according to the Associated Press.

Authorities have identified two suicide bombers in the attacks as brothers Khalid and Brahim El Bakraoui, the AP reports.