BRUSSELS -- When Annelaure Leger dropped off her two children at school on Wednesday, it was like nearly every other day -- except for the machine-gun-toting policeman.

After a two-day school shutdown sparked by a threat alert across the Belgian capital, Brussels resident Leger was relieved that classes were back in session, even though she and her kids had to take their bikes since the subway was still not running in her neighbourhood.

"It was like Christmas come early for the children," Leger said. "They stayed at home and played with the neighbours' kids." She said the family lives partly in Paris and that the children are very aware of what's happening both there and in Belgium.

"It would be better if the police had caught the terrorists, but the children know they are trying to do that so that everyone is safe," she said.

Though the Belgian capital continues to be under the highest-level threat alert, meaning that authorities fear a serious and imminent attack, schools and subways began reopening across the city on Wednesday. That is restoring a sense of normality in the city, parts of which have been deserted since the alert was first raised to the top level in the capital on Saturday.

The threat level is expected to be in place until at least Monday unless there are significant developments, like the capturing of some suspects linked to the Paris attacks on Nov. 13, who are believed to be in Belgium.

Some experts warned that without a further explanation of the situation, officials risked undermining the public's trust.

"It seems paradoxical to say that (Brussels) is still at the highest threat level but it's OK to open schools and subways," said Neil Greenberg, a professor of mental health at King's College London. "It's not very helpful to reassure people that everything is safe without sharing more information about what has actually been done."

At Brussels' College Saint-Jean-Berchmans, many parents had a quick word with school officials or the police officers guarding the entrance before kissing their kids goodbye. Security at the upscale school is normally already very tight since Belgium's Princess Eleonore is among the students.

"I've told my children they have to be careful, but life must go on and they have to go back to school now," said Dimitri De Cra Yencour, a father of four.

At other schools in the region, officials sent parents letters and emails explaining security measures being taken under police orders, like limiting access to the school and not allowing children to play or gather in large spaces like courtyards.

Some children looked visibly worried as they arrived at the College Saint-Jean-Berchmans on a grey Wednesday morning and many were distracted by the presence of camera crews capturing the moment.

Didier Nkoy Balengola, another father, said he had explained to his children that "there are some bad men who for no reason want to hurt innocent people" but that he had confidence in the police.