Horror and panic took 21 minutes to unfold in the classrooms, corridors and staircases of the historic building of the Faculty of Arts at Charles University in the Old Town of Prague.
But the Czechs now know that the killing spree of the Prague killer did not begin there.
Before David Kozak left 14 dead at the university, he killed a father earlier that day, and is now under investigation for the murder of another man and his two-month-old daughter in a forest on the eastern outskirts of Prague a week ago.
Those murders committed on Friday, December 15 in the afternoon shocked the country.
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And although the killer's name was on the list of suspects, that list was long.
For days, the police searched the Klanovicka forest, after a witness heard the sound of gunshots.
"We were a few days away from finding the killer from the forest," Prague police director Petr Matejcek said after the shooting at the university.
Ballistic tests are currently being conducted and if they confirm that the twenty-four-year-old student was the killer, they will leave behind a trail of 17 victims in seven days.
Police have come under fire for the way they responded to the attack at the university, but she says she was working around the clock on murders in the woods and could not have predicted what was about to happen.
"We have no concrete evidence or information from him as to why he decided to do something so terrible," Interior Minister Wit Rakusan told the BBC.
He had no criminal record, nor did he have a history of violence.
At the beginning of the year, he won an award for his graduation thesis at the Polish Institute in Prague.
On Thursday, police were first notified of the crime in Hostoun, a village 20 kilometers from the capital, two and a half hours before the shooting at the university began.
U 12:26 local time, a woman called the police to say that a friend had sent her a text message saying that he was going to take his own life and that he was not answering calls, police colonel Vojtek Motika told reporters.
Sixteen minutes later, they found that he had gone to Prague, and approx 13:00 hours, the body of a man - the killer's father - was found in Houston.
Colonel Motika said that a device that could be a bomb was found in the house.
U 13:15 a national manhunt for the missing student was launched, and in 13:27 Prague police received a warrant to search for an armed suspect, who is believed to be at the Faculty of Arts in Prague.
But the faculty has several buildings, and no police unit was sent to the legendary building on Jan Palah Square, near the Vltava River.
Instead, they were all sent to Celetina Street, a few minutes' walk from the Old Town, and began to evacuate the building in 14:22.
Should they all have gone to one faculty building or spread out?
The Minister of the Interior said that at that moment they had no indication that anyone was at risk except for the shooter himself, who they said was preparing to go to a lecture.
A little before 15:00, a shooting was reported in the larger faculty building on Jan Palaha Square.
At that moment, David Vicnar, an associate professor of literature, described how he went up two floors in the elevator and was stuck in it for 15 minutes with the lights off while loud bangs echoed all around him.
During that time, the police say that it took them four minutes from the first alarm raised in 14:59 to get to the building.
The first police officers on the scene were carrying handguns.
David Vičnar describes how three armed police officers told him to lie on his stomach on the floor.
"Another person crouching in a corner told me, 'There's an armed man on the roof,'" he told Radio Prague International.
In the footage from the security officer's camera, armed police officers in protective gear can be seen climbing the college's stairs, entering classrooms and exiting onto the balconies.
Watch the video of the search for the attacker - the camera was on one of the police officers:
Many of the students managed to barricade themselves inside.
In one room, police can be seen administering first aid to some of the shooter's victims, and one can be seen being carried out of the building on a stretcher.
Among those killed was the eminent musicologist Lenka Hlavkova, who specialized in medieval music.
Just an hour earlier, she had emailed a colleague about plans for the Prague Spring music festival next May.
The shooter had a permit for eight guns, although it is not yet known exactly how many he had with him in the building.
It is unknown how he managed to get hold of such a large arsenal, and the interior minister says he could have killed many more students.
Prague Police Director Petr Matejcek described how he was in the faculty building while the attack was underway and that he was shocked by the "unbelievable" amount of ammunition in the corridors.
How he managed to bring weapons and ammunition into the building is part of the investigation.
U 15:11, the attacker was on the roof opening fire, and it took time for the police to reach him.
For the next nine minutes, students could be seen scrambling for cover, with some of them jumping from a higher sim to a lower floor.
Watch: Dramatic footage from Prague of people jumping from the sims building
Three people were wounded, while the shooter targeted a police car and another vehicle.
One man filming from the ground started shouting, in an attempt to distract the man from the students who were trying to escape.
"I'm here, shoot here, come here!"
U 15:20, the shooter was dead: He saw armed police officers coming and made a decision for himself, police say.
It took time for the police to secure the entire building, but eventually the students were escorted to safety with their hands raised as a precaution.
Fourteen students and staff members lost their lives in the attack on Charles University: 13 died in the building, while one died later in hospital.
Another 25 were wounded.
According to Czech reports, one of the victims was killed while jumping from the building, while others were injured while trying to escape.
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Bonus video:
