It took 21 minutes for the horror and panic to unfold in the lecture rooms, corridors and staircases of Charles University's historic arts faculty building in the Old Town of Prague.

But Czechs are now realising that the Prague shooter's killing spree did not begin there.

Before David Kozak had left 14 people dead at the university, he shot his father earlier the same day, and he is also now being investigated for the killing of another man and his two-month-old baby girl in a forest on the eastern fringes of Prague a week ago.

Those murders during the afternoon of Friday 15 December had shocked the country. And although the shooter's name was on a list of suspects, that list was long.

For days, police had searched the Klanovicky forest, after a witness heard shots ringing out.

"We were days from uncovering the shooter from the forest," said Prague police director Petr Matejcek after the university shootings.

Ballistics tests are being carried out, and if they confirm the 24-year-old student was the killer, he will have left behind a trail of 17 victims in seven days.

Police are facing criticism for their handling of the university attack, but they say they had been working 24 hours a day on the forest murders and could not have foreseen what was coming.

"We don't have particular proof or information from him why he decided to do something so terrible," Interior Minister Vit Rakusan told the BBC.

He had no criminal record, no history of violence. Earlier this year he had won a prize for a bachelor's thesis from Prague's Polish Institute.

It was more than two and a half hours before the university shootings began on Thursday that police were first alerted to a crime in Hostoun, a village 20km (12 miles) west of the capital.

At 12:26 local time, a woman called police to say her friend had sent her a text saying he was going to take his life and was not responding to calls, Police Col Vojtech Motyka told reporters.

Sixteen minutes later, they determined that he was heading to Prague, and at about 13:00 a man's body - the shooter's father - was recovered in Hostoun.

Col Motyka said a device in the house was found that might be a bomb.

At 13:15 a nationwide search was launched for the missing student, and at 13:27 Prague police were asked to search for an armed suspect, presumed to be at the faculty of arts in Prague.

But the faculty has several facilities and no police units were sent to the iconic building on Jan Palach Square, close to the Vltava river. Instead, they were all sent to Celetna Street, a few minutes' walk into the Old Town, and began evacuating the building at 14:22.

Should they have all gone to one faculty, rather than spreading out? The interior minister said at this point they had no indication of anyone else at risk other than the shooter himself, who they were told was due to attend a lecture.

Just before 15:00, shooting was reported from the larger faculty building on Jan Palach Square.

It was at that moment that David Vichnar, an assistant literature professor, described going up two floors in the lift before becoming stuck there for 15 minutes with the lights out while banging noises went on around him.

Meanwhile, police say it took them four minutes from the first alert at 14:59 to enter the building. The first officers on the scene were carrying handguns.

David Vichnar describes being told by three armed officers to lie face down on the ground. "There was another person huddled in the corner who told me, 'There's a shooter on the roof,'" he told Radio Prague International.

Bodycam footage shows armed officers in protective gear climbing the stairs of the faculty, entering classrooms and going on to balconies. Many of the students had managed to barricade themselves in.

In one room, police are seen treating some of the shooter's victims and one is seen being carried out of the building on a stretcher.

Among those killed was eminent musicologist Lenka Hlavkova, who specialised in medieval music. Only an hour before, she had sent an email to a colleague about plans for the Prague Spring music festival next May.

The shooter had a licence for eight guns, although it is not yet clear how many he had with him inside the building.

It was unknown how he was able 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 being inside the faculty as the attack unfolded and being shocked at the "incredible" piles of ammunition in the corridors. How he managed to bring his guns and ammunition into the building is part of the investigation.

By 15:11 the attacker was on the roof and opening fire and it took police time to reach him.

Over the next nine minutes, students are seen scrambling to safety, some of them leaping from an upper ledge to a lower floor.

Three people on the ground were wounded, as the gunman targeted a police car and another vehicle.

One man filming from the ground shouted out, attempting to distract the man from the students trying to escape. "I am here, shoot here, come over here!"

At 15:20, the shooter was dead: he saw armed officers coming and turned the gun on himself, say police.

It took some time for them to secure the building, but eventually students were escorted to safety with their hands raised as a precaution.

Fourteen students and staff lost their lives in the attack on Charles University: 13 were murdered in the building, while another died later in hospital. Twenty-five others were injured.

Czech reports said one of the victims had died falling from the building and others had also been hurt trying to escape.