Zdeněk Konopka, a 54-year-old man from the Czech Republic, had a documented history of criminal behavior and violence prior to the Bohumín arson attack. He had been convicted four times, with two prior convictions for violent offenses. He was reportedly known in his community for frequent aggression and heavy alcohol consumption. Several weeks before the fatal arson attack in August 2020, he had been involved in a threatening confrontation at a nearby lake, where he used a gas pistol to intimidate his estranged wife and son. Though the weapon was not capable of causing lethal injury and he could not legally possess firearms due to his record, the police investigation into that threat remained ongoing at the time of the fatal attack. Following this incident, his estranged wife moved in with their son into the same apartment that would later become the target of his deadly attack.

Konopka was not invited to his soon-to-be daughter-in-law’s 30th birthday party, which was being held at his son's flat in Bohumín, a city in the northeast of the country. Witness reports and court records confirm that he planned the attack in advance, deliberately fueled by a desire to retaliate over unresolved family disputes.

On 8 August 2020, Zdeněk Konopka carried out one of the deadliest mass murders in post-WWII Czech history. He had filled two plastic bottles with gasoline a total of 8 liters at a nearby petrol station and proceeded to the 11th floor of a 13-story apartment building located on Nerudova Street in Bohumín. There, his son, grandson, estranged wife, and numerous other people were gathered for a birthday celebration to which he had not been invited. Witnesses later confirmed that the apartment was crowded and lively when he arrived at the door.

Standing at the entrance, Konopka rang the bell while holding the gasoline bottles. A woman whose name was not publicly disclosed opened the door. In response, Konopka threw one of the open bottles at her. As she slammed the door shut, he poured the remaining gasoline on the entrance, allowing some to flow underneath the door into the apartment interior. He then ignited the fuel, triggering a flash fire that spread rapidly due to the high volume of accelerant and lack of escape routes.

The fire quickly consumed the flat, trapping those inside. Six people died in the blaze, while five others jumped to their deaths from windows in a desperate attempt to escape. All five victims who jumped were already on fire. Casualties included three children, and most of the victims were either related to Konopka or closely connected to his family.

Emergency services were alerted at 17:46 CET, and local fire units arrived within minutes, followed by reinforcements from Karviná, Orlová, Ostrava, and two local volunteer brigades. Despite a massive rescue operation involving 46 firefighters, nine fire engines, and three ladder trucks, the fire was not brought fully under control until 18:30, and not extinguished completely until 19:43. By then, eleven people had died, and fifteen others were injured, including two firefighters. Among the injured were Žaneta, the mother of two of the deceased young women, and Rostislav, who suffered burns while attempting to hide in a bathroom.

Konopka himself sustained burns to his hands and legs. He exited the building and was arrested at the scene by police without resistance. Two days later, he was formally charged with multiple counts of murder and public endangerment.

According to the remand filing by State Attorney Michal Król, the attack was premeditated. Konopka had intentionally consumed alcohol to embolden himself before carrying out the killings, fully aware of who was present in the flat. The prosecution described the act as calculated, intentional, and motivated by long-standing interpersonal and familial conflict.