A 22-year-old French citizen was detained in Warsaw after entering a restricted tunnel of the city’s first metro line, causing major disruption to public transport and prompting an extensive police and security response.

The incident took place on Wednesday morning, June 24, on the M1 metro line. According to Warsaw Metro officials, alarm systems detected an unauthorized person in the tunnels between the Ursynów and Służew stations shortly after 7 a.m. The man was later stopped by police as he was leaving the tunnel near Służew station.

The disruption came during the morning rush hour and affected thousands of commuters. For several hours, trains on the M1 line operated only on a shortened route between Młociny and Politechnika, while 10 stations on the southern section of the line were closed. The suspended stations included Pole Mokotowskie, Racławicka, Wierzbno, Wilanowska, Służew, Ursynów, Stokłosy, Imielin, Natolin and Kabaty. Replacement buses and trams were introduced to help passengers continue their journeys.

Police and metro services treated the situation seriously, as any unauthorized presence in a metro tunnel creates a potential threat both to the intruder and to passengers. Officers checked the tunnels for possible luggage, suspicious objects or damage to infrastructure. Pyrotechnic checks were also carried out. No danger was found, and regular train traffic was restored shortly before 11 a.m.

The man’s motives remain unclear. Police later confirmed that the detainee was a 22-year-old citizen of France. According to officers, he refused to answer questions and did not explain why he had forced his way into a protected part of the metro’s technical infrastructure.

Because of his lack of cooperation, police decided later in the day to carry out another, broader inspection of the Służew station, its back office areas and technical infrastructure. This led to a second temporary closure of the same section of the M1 line in the afternoon. The additional disruption lasted around one and a half hours.

No injuries were reported. Authorities also said they had no confirmed information at that stage about serious damage to metro infrastructure, although the circumstances of the incident were still being investigated.

The episode highlighted how vulnerable a large urban transport system can be to even a single unauthorized intrusion. In a city where the metro is one of the most important means of daily transport, the presence of one person in a restricted tunnel was enough to paralyze a significant part of the network.

Warsaw police are continuing their investigation into how the man entered the tunnel and why he did so. Further proceedings with the detainee were expected after his identity was confirmed.