Police say he drove a car straight into the square and shot at random people.
That's everything we know.
Why this mattersSo here's what we know about how it happened.
A tram was passing nearby. He shot at that too. The driver's cabin window shattered.
Police say the gunman is a Polish citizen. He acted alone.
He was wearing military-style fatigues. He was carrying a military-type long gun. And police found a lot more weapons and ammunition in his car.
Here's how it ended. Police caught up with him a short distance away. He fired back. They shot him. Two police officers are among the wounded.
He's now in custody, getting hospital treatment.
And the death toll has moved already. It started at five. Now it's six confirmed dead.
Police have knocked down two rumours going around. No, an officer did not die. No, there is no second suspect. Just the one gunman, and he's already in custody.
So why does this matter beyond Kraków?
Because mass shootings almost never happen in Poland. This is a NATO country. An EU country. 38 million people. And this just doesn't happen there.
And this square is not just any square. It's called Rynek Główny. It's Kraków's historic centre. About 15 million tourists pass through Kraków every year, and most of them walk through this exact square.
Kraków is Poland's second-biggest city. It sits about 250 kilometres from Warsaw, the capital.
Donald Tusk, Poland's Prime Minister, says he's being briefed by the Interior Minister. He says police are digging into the background of the attack. Marcin Kierwiński, the Interior Minister, has already flown to Kraków to meet security officials face to face.
Karol Nawrocki, Poland's President, says his thoughts are with the victims, the wounded, and their families.
Tom Rose, the US Ambassador to Poland, says quote "savage and murderous attack that's shattered the peace of Poland". He says America stands with Poland.
Kaja Kallas, the EU's top diplomat, says this tragedy will be felt far beyond Poland. Volodymyr Zelensky, Ukraine's President, has also sent his condolences.
A Polish Medical Air Rescue helicopter landed right there in the square to treat the wounded.
So three things are still open. Who is this man, really? Why did he do it? And will this be called terrorism?
Police have only answered one question so far. There's no second attacker.
Everything else, we're still waiting on.
