WARSAW, Poland (AP) — Police in the Polish capital on Saturday detained a man who climbed the top of a monument and reportedly threatened to blow himself up.

Large numbers of police and special counterterrorism officers sealed off a large square where the man had shouted something through a megaphone for hours. An Associated Press photojournalist nearby could see him could not hear what he said.

The incident ended when he climbed down from the monument without anyone being harmed. Polish media said he was detained.

The incident took place at Pilsudski Square, the site of the memorial to late President Lech Kaczynski and the dozens of other victims of a plane crash near Smolensk, Russia.

The man’s intentions and whether he had an explosive device were not immediately known.

The incident came on the eve of a critical national election.

The country’s de facto leader is Lech Kaczynski’s surviving twin, Jaroslaw Kaczynski, while his ruling Law and Justice party is fighting for an unprecedented third straight term.