Attackers may have tried to destroy evidence as they set fire to a laboratory at Belgium’s crime institute.
The perpetrators rammed through gates to break into the facility before starting the blaze in the capital Brussels.
The fire in the early hours of Monday caused an explosion but there were no casualties.
Part of the building was scorched and a burnt-out car was later lifted from the scene by a crane.
Belgian media reported there had been a bomb attack, but investigators said the noise was probably due to materials burning.
Five people were arrested nearby over the incident but they were later released.
Ine Van Wymersch, a spokeswoman for the Brussels prosecutor’s office, said it was probably not terrorism and was more likely a criminal act.
She said “several attackers forced their way into the institute using their car and were able to attack the building”.
They had apparently deliberately targeted the wing where the laboratories are located in Neder-Over-Hembeek, a northern suburb of Brussels.
Ms Van Wymersch said the location was not chosen randomly and the lab contains sensitive information being used in ongoing investigations.
Among the institute’s tasks is carrying out forensic analysis for criminal cases.
She said: “The laboratory does thousands of analyses each year, so we don’t know what damage has been done yet.
“It is obvious that several individuals would have an interest in making elements in their justice file disappear.”
Belgium has been on high alert since suicide bombings at the Brussels airport and subway killed 32 people on 22 March, and security forces remain on standby for another attack.
The police and army have been deployed in large numbers since suicide bombers attacked Paris last November, leaving 130 dead. Many of the attackers had links to Belgium.
Original source: Sky News