Greek police announced Monday that explosives experts had defused a bomb at the Thessaloniki Courthouse that had been sent in an envelope to a senior judge. The judge had alerted the police to the suspicious package and, after carrying out x-rays, it was found to contain explosives.

According to local media sources, the envelope contained gelatinous dynamite, an explosive material that was neutralized at the scene. The courthouse was comparatively empty due to lawyers’ strikes in the country, but the remaining people were evacuated while the operation took place.

The Directorate for Dealing with Special Violent Crimes of Thessaloniki will now take over the investigation in an attempt to find out who sent the package. While it is unsure who is responsible and no groups have claimed responsibility, there have been similar attacks in the past against Greek courthouses. An attack in December 2017 by a far-left group caused extensive damage to an Athens courthouse, but no one was injured. At the time, the group responsible had said they were protesting the alleged biases of Greek judges that apparently favored the wealthy and influential in a series of high-profile cases.