Alexander Pinczowski was excited about attending a North Carolina wedding later this week with his longtime sweetheart. First, though, he and his sister, Sascha, had to get home to New York City from Europe, where they were visiting family.

The last time anyone heard from them was a Tuesday morning phone call to their family made from the Brussels, Belgium airport just before the terrorist attacks that left 35 people dead.

A relative heard glass shattering before the call dropped, according to Dutch newspaper Algemeen Dagblad. Then the line went dead.

The brother and sister haven’t been heard from since.

Now friends and family are frantically searching for Alex and Sascha.

“Their mother is worried sick since she can’t get hold of them since this morning when they were checking in at Zaventem airport … at 8.30 this morning,” Mafalda De Andrade Vasconcelos [who appears to be a family friend] wrote on Facebook yesterday.

Alex is “such a great guy,” said Laura Cain, sister of Alex’s girlfriend of six years, Cameron Cain, “He’s like my older brother.”

“Alex and Cameron were supposed to be flying in [to North Carolina] tonight because they have a wedding Friday for a friend here,” Laura Cain, 24, of Raleigh, said in a phone interview with The Daily Beast on Wednesday.

“I really hope they’re OK. I want [Cameron and Alex] to get married one day,” she said. “They’re so much in love, and they’re wonderful.”

The Pinczowskis are among at least four Americans, including a Kentucky couple, reported missing since the Tuesday morning attacks on the Brussels airport and metro stations that killed 35 people and injured more than 200 injured.

On Wednesday, a State Department spokesman said about a dozen Americans were injured in the blasts, but that he couldn’t confirm whether any U.S. citizens were killed.

“Obviously, it’s a very fluid situation on the ground there,” State Department spokesman Mark Toner told CNN. “We’re still getting information, we’re still trying to seek out the whereabouts of American citizens.”

Laura Cain told The Daily Beast that her parents had flown to New York to be with her panic-stricken sister, while friends and relatives are taking to social media to spread the word about their missing friends.

On Tuesday, Cameron Cain posted a plea on Twitter to help find her lost beau.

“Please help find my boyfriend and his sister Alex Pinczowski Sascha Pinczowski,” she said.

In another post, she wrote, “My bf & his sis are still missing since this morning. They were in the departure hall at time. Please help.”

The Pinczowskis were born in Greece to Dutch parents and are Dutch citizens, according to Facebook posts by friends.

Alex and Sascha’s parents moved back to the Netherlands about seven years ago, after spending three decades abroad. Their father, who had worked in the hotel industry for decades, works as a lecturer in the hotel management school at Maastricht.

Sascha was a 2014 graduate of Marymount Manhattan College, where she got a Bachelor of Business Administration degree with a focus on arts, entertainment, and media management, according to her LinkedIn page. She was most recently a production intern at Shiraz Events in New York.

One of her coworkers at Shiraz told the New York Post that Sascha was an “awesome chick” and a “problem-solver.”

“She liked to have a good time—and had a lot of friends,” Florencia Sadler said. “She was very determined and fun. She was a pleasure to have around.”

Another friend of Sascha’s, Alex Kneeshaw, told the Daily News she’s known the Pinczowskis for 15 years and lived with them in Germany.

“She is the kindest, goofiest, and down-to-earth girl I have ever met,” Kneeshaw told the News. “She is the only friend that after a year or two of not seeing her we could sit down and act like no time had passed.”

A slew of emotional Facebook posts identified Sascha as a best friend to many women.

Laura Cain said Alexander has been a big part of her family, accompanying them on a vacation to Scotland and visiting North Carolina on holidays.

During one Christmas, Alexander and Cameron picked out Winston, a whippet puppy, to surprise Cameron’s father. The rescue dog has become the family’s beloved pet, Laura Cain said.

“Cameron and Alex … were living in Durham, and they just fell in love with him,” Cain said. “We’re so happy they brought Winston in our lives.”

“It was both of their ideas,” the sister added. “They love surprises.”

Cameron, who works in external affairs at the Asia Society, and Alexander are inseparable, Cain said. They go clay pigeon shooting together, explore old book stores, and discuss current events.

“They have a great friendship. Of course, they’re in love, but they do so much together,” Cain told The Daily Beast. “They have a passion for life.”

Cain described Alex as a family man who would do anything for his girlfriend.

“He is really outgoing. He is so smart, intelligent, and culturally aware of what’s going on in the world. He loves animals, and he thinks about others before he thinks about himself,” she said.

Photos: The World Mourns With Belgium