Poland began two days of national mourning on Sunday, and police ​bolstered security after six people were killed in a mass shooting in Krakow that authorities said was likely ‌inspired by far-right ideology. Saturday's attack in the city's historic main square shocked a country that has prided itself on being safer than many of its Western European neighbours, deepening public concern following a string of school stabbings in October that officials linked to extremist content online. Seventeen people, including ​two police officers and the gunman, were wounded in the attack, authorities said. The 24-year-old suspect's parents and sister were ​later found dead at their home, and he remained in hospital in a critical condition, ⁠police and a local official said. Streets closed as mourners leave candles  In Krakow, the old town's main market square and the ​surrounding streets remained closed, with police allowing only essential workers to pass. Many nearby cafes were closed, and flags at the ​city hall were at half-mast. Mourners placed candles in several locations in the area. The traditional trumpet call from St Mary's church on the square was suspended for 12 hours to commemorate the dead, the first time this has happened since 1939, the state news agency PAP reported. Read: Six people killed by Polish gunman In the capital, ​Warsaw, police said on Saturday they were strengthening security measures in busy areas popular with tourists. Barriers were installed on ​streets leading onto the Krakowskie Przedmiescie street in the historic heart of the capital. In the suspect's hometown, Ostrowiec Swietokrzyski, about 200 km (124 ‌miles) north ⁠of Krakow, police said they had found the bodies of his parents and sister and that investigations were ongoing. "Yesterday, before 22:00, we discovered the bodies of three individuals - a 53-year-old man and two women, aged 52 and 21 - in an apartment located in a residential building in the centre of Ostrowiec Swietokrzyski," police wrote on X. Attacks shatter sense of security  Maria, a 20-year-old Warsaw ​cafe employee, said she "almost burst ​into tears" when she ⁠heard about the attack in Krakow. "Recent events - not just this one, but things happening lately - are really affecting our sense of security," she said. Leading daily newspaper Rzeczpospolita said in an editorial ​that the mass shooting brought a "brutal end to an era in which Poland was considered ​an island of ⁠safety". Besides expressing shock at the killings, officials and members of the public praised the actions of police officers who apprehended the gunman after a close-range shootout. Read more: Polish security services meet after 'serious' threat to PM and defence minister Two officers were wounded, and police issued an urgent appeal for blood for one of them, who was "fighting for ⁠his life ​in hospital". "Senior Constable Jakub Kulik and Senior Constable Artur Moranski are true ​heroes," Prime Minister Donald Tusk said on Saturday in a post on X. "They likely saved many human lives, disregarding the risk to their own."