BRUSSELS (TheBlaze/AP) -- The Belgian government has ordered health and emergency services in the country to take special precautionary measures to make sure their services are not infiltrated by violent extremists.
Health Minister Maggie De Block told VRT network that "we have to be sure that we can see everybody has an identification badge."
She says, "When ambulances arrive, we have to see from where they come, who is in it. Really as a precaution."
This move comes as Brussels continued an alert of the highest level, prompted by a "serious and imminent threat."
As a police officer stands guard, a man kisses his child goodbye outside the entrance of a school in the center of Brussels on Wednesday, Nov. 25, 2015. Students in Brussels have begun returning to class after a two-day shutdown over fears that a series of simultaneous attacks could be launched around the Belgian capital. (AP/Virginia Mayo)
Interior Minister Jan Jambon told VRT network that if a threat was not considered "serious and imminent," then "you don't impose terror level 4," the highest possible threat level.
The minister said security forces staged a series of raids late Sunday to avoid an imminent attack in Brussels.
"Indeed, there were indications that there would be attacks on Sunday evening and they did not materialize," Jambon said.
Authorities detained 16 people Sunday but released all but one the next day. The raids yielded no explosives or firearms and the Paris attack fugitive Salah Abdeslam remained at large.
Jambon refused to elaborate what kind of attacks the government believed had been planned.
A shutdown in the Belgian capital has been imposed for four days as the threat alert continues, but schools and subways opened Wednesday with heightened security, which included police armed with machine guns.
This gradual reopening is restoring a sense of normality to the city, parts of which have been deserted since the alert was first raised to the top level in the capital on Saturday.
"I'm concerned, but I think that life must go on," Dimitri De Cra Yencour, a father of four, said. "Even if something happens in Paris or in Brussels, they have to go back to school," he said, adding he had instructed his children be extra attentive and to tell their teachers if they saw anything unusual.
A man wheels a boy on his bicycle past police officers as they arrive for school in the center of Brussels on Wednesday, Nov. 25, 2015. Students in Brussels have begun returning to class after a two-day shutdown over fears that a series of simultaneous attacks could be launched around the Belgian capital. (AP/Virginia Mayo)
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 upscale Brussels school but most gave a friendly handshake to a burly school official guarding the entrance alongside the police officers.
Father Didier Nkoy Balengola said he had explained to his children that "there are some bad men who for no reason want to hurt innocent people" but he had confidence in the police.
The threat level is expected to be in place until at least Monday unless there are significant developments, like the capturing of suspects linked to the Paris attacks on Nov. 13.