Five suspects in an overnight arson attack on a Belgian crime investigation centre were released Monday following questioning, prosecutors said, without giving details on the ongoing inquiry into the incident.
At around 2 am (0000 GMT), a fire broke out at the National Institute of Criminalistics and Criminology (NICC) on the edge of Brussels, where the judiciary carries out forensic examinations, the city's crown prosecution service said in a statement.
Several perpetrators had used a car to break into the premises. The building suffered severe damage but nobody was injured, as the site was empty at the time.
"This location was not chosen randomly," the prosecution said, noting that the NICC holds "sensitive information concerning several ongoing investigations and legal cases."
The possibility of a terrorist attack "has not been confirmed," its statement added.
Media initially said that a bomb had exploded at the institute. The prosecution said it was looking into witness reports that they had heard explosions, noting that the origin was not yet clear.
The five suspects had been detained in the "immediate vicinity" of the NICC right after the offence took place, the prosecution said earlier Monday. They were released without charge.
An investigation has been opened into the charges of arson and causing damage caused by explosion.
"It goes without saying that several individuals would benefit if elements from their legal cases were destroyed," the prosecution statement said, noting that "all possible scenarios are being considered."