Belgian police have arrested five suspects after a blast on Monday at the country’s national crime lab just north of Brussels caused major damage but no casualties, prosecutors said, dismissing reports that a bomb had exploded.

They said there was no immediate reason to believe there was any terror link and it could easily be a case of criminals trying to destroy evidence.

The blast happened in the early hours of Monday at the national criminology institute in Neder-Over-Hembeek, which is linked to the Belgian ministry of justice and carries out forensic investigations in criminal cases.

“Five people were arrested in the immediate neighborhood… They are currently being questioned to see if they had any role in the incident,” Ine Van Wymersch, a spokeswoman for the Brussels’ prosecutor’s office, told a press briefing.

The official described the incident as more likely an arson attack designed to destroy criminal evidence.

“It’s probably not terrorism. It’s a criminal act,” said Wymersch. “I cannot confirm that there was any bomb.”

“The location was not chosen randomly,” Wymersch added, saying the lab contains “sensitive information” being used in ongoing investigations.

Press reports say a car was rammed through the gates and into the building which was set on fire, leading to several explosions in the lab.

Belgium is still on high alert after deadly ISIS-claimed attacks in March.

Belgium’s police and army have also been deployed in large numbers since suicide bombers attacked Paris last November. Many of the attackers had links to Belgium.

Tensions have also been running high in the country in recent weeks amid a series of criminal knife and shooting attacks and two hoax anthrax attacks.