The attack began shortly before 3 p.m. on Saturday in the Main Market Square in Krakow's Old Town. According to several media outlets, the popular tourist destination was packed with people at the time.
Police said the perpetrator drove into the square and began shooting indiscriminately at people from his car.
Witness accounts indicate that he used several different weapons.
Police arrived quickly, and just three minutes after the attack began, the man was shot, preventing an even worse massacre, according to Polish authorities.
The suspect survived and was arrested. He is still being treated in hospital for his gunshot wounds.
At least nine dead
Six people - four women and two men - were killed in the attack, and around 15 are being treated in hospital. One of the dead is a British citizen. In addition to Poles, the injured include people from Austria, Germany, Portugal, Russia and the UK.
Two police officers were shot in the exchange of fire. One is being treated for critical injuries, according to authorities.
Three more bodies have been found in the perpetrator's home in a town about ten miles from Krakow. According to authorities, they are the suspected shooter's parents and 21-year-old sister.
"Right-wing extremist ideologies"
Police have identified the arrested man as a young Pole.
Authorities have described the shooting as an act of terrorism in which the man acted alone. Police said he was armed with military-style firearms. A large amount of weapons and ammunition was found in his car.
He is also said to have been wearing military uniform during the attack. However, he is not said to have been a soldier.
According to Poland's interior minister, the initial investigation indicates that the suspect sympathizes with "right-wing extremist ideologies." The minister also described him as an ultranationalist.
What do you think?