The police in Finland are investigating the explosion of a homemade bomb set off in Lapua on Monday.
Officials have not yet found the four young men suspected of setting off the "pipe bomb" in the foyer of the Lapua library, but have obtained CCTV footage of the perpetrators.
Police are also investigating a possible link between the explosion and Lapua's Pride week, which was taking place at the same time.
The Pride event was the first of its kind in Lapua and featured, among other things, a parade, picnic, workshops, art, bowling, and burlesque performances.
"Library staff have informed the police that the same people have previously caused a disturbance there. They had been reprimanded and apparently were upset about it. After that, a homemade bomb was detonated in the hall closet," said Detective Inspector Kati-Susanna Lukkarinen.
The motive for the acts is still unknown.
"No link to the Pride event has yet been established. The investigation currently focuses on criminal damage and causing danger," Lukkarinen told Yle.
Library staff have given police a description of the suspects and Lukkarinen said he is confident that they will be found quickly and taken into custody for interviews and interrogations.