Poland's interior minister, Marcin Kierwiński, said the suspect held "very radical" and "ultra-nationalistic" views. ( Reuters: Jakub Porzycki )
The gunman who killed six people and injured 15 others in central Krakow has died in hospital.
Polish prosecutors said the mass shooting is being treated as an act "constituting a terrorist offence".
The Polish government has vowed to review the requirements and regulations governing gun permits.
A gunman who killed six people and injured 15 others in a mass shooting in central Krakow, Poland, has died in hospital.
The man was shot by police officers and arrested minutes after he opened fire on people from his car in Krakow's historic main square on Saturday, local time.
Polish prosecutors said on Sunday the attack is being treated as an act "constituting a terrorist offence".
The square reopened on Sunday evening, with mourners gathering to lay flowers and candles in honour of the victims. ( Reuters: Jakub Porzycki )
The government had said the assailant, identified as Michal O, a 24-year-old from the town of Ostrowiec Swietokrzyski in south-eastern Poland, may have been inspired by far-right ideology, without providing further details.
The incident sparked a bitter political dispute over his motives, with Poland's nationalist opposition criticising the government's statement about far-right ideology.
Law & Justice party leader Jaroslaw Kaczynski said the claims were a "blatant lie".
Polish prosecutors say the shooting is being treated as an act "constituting a terrorist offence". ( Reuters: Jakub Porzyck )
On Monday, government officials appeared to walk back from the initial comments.
"Until the matter is fully clarified and the authorities are in possession of complete information, it is best to refrain from making comments, even if there are some initial indications," government spokesperson Adam Szlapka told local news.
Justice Minister Waldemar Zurek said on Monday that despite the death of the shooter, the investigation would continue, aiming to establish whether he acted alone or was inspired by any group.
"Evidence is being collected, but I will not show or disclose it. I ask for restraint," Mr Zurek told Radio Zet.
An interior ministry spokesperson said earlier on Monday there were many different emblems on the perpetrator's clothing that had already been partially examined and interpreted.
Four women and two men were killed in the shooting . Three of the women and one of the men were Polish, according to Malopolska regional governor Krzysztof Jan Klęczar.
A man from the United Kingdom and a woman from Austria were also among the dead, authorities said.
The bodies of the shooter's father, mother and sister were found in their family home on Saturday, and officials said they were also likely killed by Michal O.
About 411,000 people hold gun permits in Poland, which has a population of 37 million. ( Agencja Wyborcza: Jakub Włodek via Reuters )
A video posted on social media showed a police officer repeatedly shooting the attacker, who was lying on the street. The officer later slowly collapsed to the ground.
Of the 15 injured in the attack, 14 remain in hospital in a stable condition.
A police officer who assisted in apprehending the shooter remains in a serious condition, according to Krakow Province Governor Krzysztof Kleczar.
The Polish government will review regulations on requirements for people with gun permits following the tragedy, Mr Zurek said.
Both the shooter and his father had gun permits, and several firearms were found in the family apartment and the assailant's car, prosecutors said.
