Flowers and lit candles lie on a street in Krakow, as Poland observes two days of national mourning following a mass shooting. (EPA Images pic)KRAKOW: Poland on Sunday launched a terrorism probe as mourners brought candles and flowers to Krakow's cordoned-off Main Market Square in tribute to six people killed by a gunman who authorities said was "fascinated by far-right ideologies".

The 24-year-old Polish man opened fire apparently at random Saturday in the historic centre of the country's second city, in what prime minister Donald Tusk called an act of "terrorism".

UN secretary-general Antonio Guterres condemned the shootings, expressing "his deepest condolences to the families of the victims, as well as to the Government and people of Poland", his spokesman said in a statement Sunday.