The perpetrator has been shot and taken to hospital, police said, AFP reports. The man is said to have driven into a square in Krakow's old town and opened fire.
The motive is still unclear.
Prime Minister Donald Tusk writes on X that he has been informed of "a tragic shooting".
"The police are investigating the background and all circumstances surrounding the attack," he writes.
Krakow in southern Poland is the country's second-largest city.
What do you think?