NEWBURY, Mass.  — At 4:42 a.m. yesterday, when Plum Island mom Holly Cassidy heard the special sound of a text from her 20-year-old daughter who is studying in the Netherlands, she made a note to open it as soon as she rose for the day.

What she read was enough to stop a parent’s heart, then start it again.

“It said: ‘Hi Mom, there was an explosion at Brussels Airport and Ryan and I were on our way there,’” Maddie Cassidy wrote. “Want to let you know we’re OK and going back to Maastricht now.”

Needing to get her two other children off to school without alarming them, Cassidy kept it together, although she couldn’t reach Maddie by cellphone. It was her faith in her daughter’s common sense, she said, that kept her as calm as any parent could be while listening to the horror being reported by every news channel in the world.

Maddie is a student at Worcester’s Clark University, with a double major in philosophy and global environmental studies. She is doing a semester abroad at Maastricht University, which is located in the south of the Netherlands, only about 90 minutes from Brussels.

Cassidy said Maddie’s boyfriend, Ryan Dupont, had flown over during his spring college break to see Maddie, and yesterday the couple had planned to travel to Brussels by train.

“Brussels is a wonderful city,” Cassidy said. “They were taking the train and there’s a required stop and transfer at the train station in Liege, Belgium, before you get another train to take you into Brussels. When they got off the train, the station was quiet. Then it erupted into confusion as news of the explosions spread.”

When Maddie turned on her WiFi at the train station, she found a bunch of messages from friends warning her of the explosions, Cassidy said. 

According to news reports, there were three explosions for which the terrorist group ISIS has claimed ownership. All three explosions occurred during rush hour Tuesday morning: two at the departure hall at the airport in Zaventem at 8 a.m., and the third at a metro station near the downtown Brussels headquarters of the European Union. As of early yesterday evening, 31 people had died as a result, with at least 250 believed injured. 

When she finally was able to get a call through to her daughter, it was around noon Newburyport time, with Belgium about five hours ahead of our time. Maddie was already back at college, Cassidy found to her relief.  

“When I got hold of her, she was in her room doing her homework, because that’s the way Maddie is,” Cassidy said. 

A paralegal with an Andover company, Cassidy said Maddie told her she’d quickly rerouted their day’s excursion back to Maastricht, but even as she walked up to the ticket counter, the clerk there hadn’t heard of the terrorist attack. But within minutes, the news broke throughout the train station. There, and throughout the small European country of Belgium, chaos grew, her daughter told her. 

The worst attack on the nation since World War II, it led to cellphone service disappearing for some time, either because the nation’s officials terminated it so other ISIS terrorists couldn’t speak to each other and coordinate more attacks, or because the blasts had crashed the system.

Cassidy said Facebook came through for the families of those abroad. The social media site created a page on which people could mark themselves as “safe.” Those who couldn’t get hold of their loved ones in Europe could visit the Facebook page.

As for her daughter, Cassidy said, she still wants to travel to Italy to be at the Vatican for Good Friday.

“Right now, that’s still the plan,” Cassidy said.

Chiaramida writes for the (Massachusetts) Newburyport news.