Film student Manon Duwelz, 21, was in class on Tuesday morning when she found out on Facebook that the international airport and a metro station near her school had been bombed.
Soon after, teachers came around to tell the class to stay put, before locking the doors.
Mobile networks were jammed and for two hours, she could not phone home. As the entire city was locked down and public transport came to a standstill, the school arranged for buses to take students who live outside of Brussels home.
It was not until 4pm that the school felt confident to let them leave. "It was bound to happen," said Ms Duwelz. "But it was still frightening."
Last Tuesday morning, Brussels woke up to terror when several men blew themselves up with nail bombs during the morning rush hour, killing 31 people and injuring more than 300 at the airport and a busy metro station near the European Union headquarters.
Brussels attacks NOT GIVING IN TO FEAR
We have to keep our heads cool and live on. We shouldn't give them (the terrorists) what they want, which is fear.
FREELANCE FILM-MAKER KHAEL V, who believes that another attack might be on the cards.
It was the worst attack in the country since World War II - one, as it has emerged in the days that followed, that Belgium was not entirely prepared for. Shock rippled through the city of 1.8 million. Belgians had thought that they could heave a sigh of relief when Salah Abdeslam, the sole survivor of a 10-man team that killed 130 people in the November Paris attacks, was captured just four days earlier in a Muslim neighbourhood in Brussels.
"This isn't something we're used to," said a lawyer in his 50s. "It's never really happened to us before."
The last terrorist attacks he remembered in the country happened in the mid-80s, when the Cellules Communistes Combattantes, or Communist Combatant Cells, targeted a series of international companies which they viewed to be enemies of communism.
But as the spotlight turned to Belgium following the Paris attacks, amid the revelation that at least four of the 10 attackers were Belgian nationals or born in Belgium, jitters started.
"You could really feel this sadness in Brussels the morning after," said Ms Lea Teheux, a finance officer for an environmental non-governmental organisation, whose office is just a 10-minute drive from Maelbeek metro station, where one of the bombs went off.
"Some of my friends told me, 'I never thought this would happen in Brussels'. But if you think about it, it's the capital of the European Union, so you can expect something awful like that to happen."
In the four days since the attacks, life is only slowly inching back to normal. The airport is still shut; metro lines are slowly being restored, with some stations still closed and services terminating at 7pm; police and military men armed with guns patrol everywhere.
Police sirens ring through the city centre while army personnel guard metro stations and ask to check bags; even on Brussels' major shopping drag Rue Neuve, security guards outside malls and major stores do the same.
But the city is quiet. Hotels bemoan that many tourists and visitors have cancelled their bookings; restaurants are woefully empty save for a table or two. When night falls, pockets of central Brussels turn into ghost towns.
At Place de la Bourse, the Brussels Stock Exchange square which has been turned into a memorial site, candles continue to burn but the number of people who turn up to pay their respects has dwindled as the days have gone by, and TV crews that thronged the plaza in the first two days have also started packing up.
But amid the grief, there is fear among the sizeable Muslim community in Brussels of a backlash that could make integration even harder than it is. About a quarter of Brussels' population are Muslims, with Moroccans and Turks making up the majority of the 300,000 in the city. All four of the terrorists in the Paris attacks who were from Brussels, including Abdeslam, were of Moroccan descent and grew up in the impoverished neighbourhood of Molenbeek. The el-Bakraoui brothers who were responsible for Tuesday's attacks were also born to Moroccan immigrant parents in Brussels.
"They keep to themselves and they organise themselves. It probably is quite easy for someone in the community to harbour the terrorists," shrugged a fry shop owner.
"I have no problems with anyone. But the Moroccans, they like to nick my fries," he said.
One Moroccan, who lives in Schaerbeek, another Muslim-concentrated borough, said he and his family are worried they may be targets now that the Paris and Brussels terrorists have given them a bad name. "They are just a few bad apples and don't represent the Moroccan community. But that is not going to stop people from hating us and thinking we are all religious fundamentalists," said the 34-year-old, who said he did not want to be named for his own safety.
Life for some will not go back to normal soon. The fear is too fresh, not helped by daily police raids and arrests such as the few in Schaerbeek after Tuesday which turned up 15kg of explosives in the el-Bakraoui brothers' flat, and a shooting on Friday.
Ms Aissatou Issa, 45, a mother of three who came from Cameroon and now runs a cafe across from the el-Bakraoui brothers' hideout in Rue Max Roos in Schaerbeek where the explosives were uncovered, still finds it hard to believe she had killers in her midst.
"You could be walking past one of them and you wouldn't even know. It's shocking, because this area is peaceful with no problems."
Even as Belgians try to get back on their feet, the country - especially its leadership - will be doing much soul-searching. In the days after the bombings, it came under an attack of a different kind - some serious knuckle-rapping by world leaders and terrorism experts who say it simply did not do enough to prevent the attacks.
Questions had also been raised over how Abdeslam could have gone undetected in Molenbeek for months after carrying out the Paris atrocities.
Intelligence and security matters aside, the country needs to look deeply into problems of neglect and integration that many believe to be the root of the problem, pushing young, marginalised men to take up arms with militant groups.
The numbers show it: An estimated 500 Belgian nationals have travelled to Syria or Iraq to fight for extremist groups like the Islamic State in Iraq and Syria, the highest number per capita in Europe according to London-based think- tank, the International Centre for the Study of Radicalisation and Political Violence.
Many, like 27-year-old freelance film-maker Khael V, believe that another attack might be on the cards.
"We have to keep our heads cool and live on. We shouldn't give them (the terrorists) what they want, which is fear."