WARSAW, Poland (AP) — Prosecutors in Poland’s capital said Wednesday they are investigating a 31-year-old man who allegedly placed what police described as a projectile in a busy Warsaw street on suspicion of terrorism.

Due to the weight of the potential changes, the National Prosecutor’s Office has taken over the investigation from regional prosecutors.

The suspect was being questioned on allegations of terrorism by causing a sense of serious threat among a large number of people, according to Karol Borcholski, a spokesperson for the national office.

If convicted of that charge, he faces up to five years in prison, or even more if the court decides. He remains in custody.

No one was reported injured, and the object did not explode. But over 300 people were participating in a commemorative march and rally for Polish victims massacred during World War II when the incident occurred Monday.

Police said after the man was detained that the explosive projectile had a potentially powerful range. An expert’s detailed opinion on its type and capability was still pending.