Police found about 50 heavy fireworks explosives in a basement storage unit beneath an apartment block on Tigrisdreef in Utrecht's Overvecht district during an inspection on 13 October. The explosives contained about 10 kilograms of flash powder and, police said, posed a major risk to nearby residents. A 55-year-old owner of the storage unit was arrested.

Police searched the man's home and found one further explosive, according to a single report. The explosives were seized and removed safely, the municipality closed the storage unit, and the investigation is ongoing.