‘Then we heard a shot,’ US tourist captures moment Prague shooter David Kozak opens fire before killing 13 at university

AN American tourist visiting Prague on a Christmas vacation captured the moment that a gunman opened fire on a busy school and public square.

Art student David Kozak has been identified as the shooter who killed 13 and wounded at least 20 others, some critically, in a sick rampage at Charles University on Thursday.

Terrifying footage shows Kozak on the roof of the university's faculty of arts building moments before he started shooting at Jan Palach Square in Prague, the capital of the Czech Republic.

He was later found dead inside the philosophy building after turning the gun on himself.

An Ohio resident on vacation in Prague captured the horrifying moments before the shooting on video.

Kevin K. - who asked The U.S. Sun to withhold his last name - described what he saw and heard in the square as the rampage began.

He was one of several bystanders who were in the square when they noticed a crowd of people running.

Kevin began filming as he saw people hurrying out of the building with their hands up over their heads.

Sirens were already blaring in the background and multiple police vehicles could be seen in the square.

"The police asked people to get behind the building since we were all just stood out in the open," Kevin told The U.S. Sun in an exclusive interview.

Police had begun evacuating the building before the shooting began after receiving a tip-off about a possible imminent attack, Czech police spokesperson Ondrej Moravcik told .

"The students you see in the video were removed from the building and were running towards us," Kevin said.

Many of those students seemed confused and unsure as to what was going on.

Other people were standing around watching the scene unfold.

Kevin's video then briefly shows the gunman atop one of the building's balconies in the upper left-hand corner of the frame.

Then, as Kevin's video followed the students across the street, gunfire echoed through the square.

He frantically lowered his phone as he realized what was unfolding.

Kevin yelled, "Jesus Christ!" before frantically lowering his camera and running from the scene around a neighboring building.

Only afterward did he understand what he'd captured.

Kevin believes he caught on video the killer's first shots.

"We didn’t realize the shooter was on the balcony. We were all just stood there, and then we heard the shot," he said.

"After that, everyone just sprinted."

'EIGHT MINUTES' OF 'INTERMITTENT GUNFIRE'

Kevin, who told The U.S. Sun that he wanted to visit some of the famous European Christmas markets, said Prague was one of several destinations on his itinerary.

"The shooting continued for at least eight minutes," Kevin said.

"[There was] intermittent gun fire. Everyone was just shocked. Everyone just ran.

"The aftermath was insane.

"Everyone was talking about it, in shock, and there were a ton of police officers everywhere."

Police quickly closed down the area, including the square and the nearby Charles Bridge.

They continued to evacuate the university as students huddled on the outside of the building for shelter.

Officials were continuing to check the area for possible explosives.

It is now the worst mass shooting in the history of the Czech Republic.

"We definitely got lucky," Kevin said of his harrowing escape.

ANOTHER MURDER

Prior to the gunfire at Charles University, police believe Kozak killed his own father.

That murder happened in their family home in the town of Kladno, located outside of Prague, Moravcik said.

Martin Vondrasek, chief of the national police force, told reporters on Thursday that Kozak “got inspired by a similar terrible event abroad.”

Vondrasek didn't further specify, but The New York Times reported that police are investigating messages posted to Telegram under Kozak's name.

While officials have not yet confirmed a definitive connection between the gunman and the messages, their content referenced inspiration from two recent Russian mass shootings.

“I was very inspired by Alina … very much,” one message dated December 10 said, referencing the December 7 mass shooting carried out by 14-year-old Alina Afanaskina.

That school shooting claimed the lives of two of her classmates.

“She certainly did not kill enough. I will try to fix that," the message continued.

Another post from the same day said: “I always wanted to kill. I thought I would be a maniac in the future.”

On December 9, one message said: “This will be my diary as I go toward school shooting.”

But that message was edited on Thursday.

The account that posted the messages to Telegram had turned private after Thursday's shooting.

Police do not believe Kozak's actions were related to domestic or international terrorism.