Czech police are working to uncover the motive behind the country's worst-ever mass shooting, which saw a student open fire at a university in central Prague, killing 14 and wounding 25 others.
Czech President Petr Pavel has appealed for unity and said the killings should not be used to launch political attacks or spread misinformation.
The victims, who have not yet been named, include the gunman's father.
Saturday has been declared a national day of mourning.
Mr Pavel expressed his "great sadness" and "helpless anger at the totally unnecessary" loss of life.
The shooting began at around 15:00 local time (14:00 GMT) on Thursday at the Faculty of Arts building of Charles University off Jan Palach Square in the centre of the Czech capital.
The gunman opened fire in the corridors and classrooms of the building, apparently killing at random, while staff and students used furniture to barricade themselves into rooms.
Dramatic footage shared on social media shows people dangling from the outside ledge of the university building before jumping to another part of the roof several metres below. Gunshots can also be heard.
In a separate video, terrified crowds are seen fleeing the city's historic Charles bridge, a major tourist attraction.
Inside the building, student Jakob Weizman used chairs and desks to barricade the door to the classroom he was in with a teacher when the shooting started.
Soon after blocking it, Mr Weizman said he heard someone trying to open the door. "He was going through each classroom to see if people were there to shoot them," he told the Guardian newspaper.
Eventually Mr Weziman and the teacher were evacuated by police. "As we were walking out, there was just blood all over the faculty," he said.
US tourist Hannah Mallicoat told the BBC that she and her family had been on Jan Palach Square during the attack.
"A crowd of people were crossing the street when the first shot hit. I thought it was something like a firecracker or a car backfire until I heard the second shot and people started running," she said.
"I saw a bullet hit the ground on the other side of the square about 30ft (9m) away before ducking into a store. The whole area was blocked off and dozens of police cars and ambulances were going towards the university."
Joe Hyland, 18 and from the UK, told the BBC he had heard four gunshots.
"Everyone was sprinting and running for cover. I have a bad knee, am on a crutch. So I hobbled as quickly as possible," added Mr Hyland, who was on his first holiday with friends. "We got to the metro and went down there because we thought it would be safest."
Police say the gunman was a 24-year-old student at the university and had no prior criminal record, though they add that a "huge arsenal of weapons and ammunition" was found.
He has been named by local media as David Kozak.
Before the shooting, police had received a report that the suspect was believed to be heading to Prague from a nearby town with the intention of killing himself.
Officers evacuated a different university building where the gunman had been expected to attend a lecture, but a short time later were called to the faculty's main building nearby.
The gunman, who police said had been "eliminated", is thought to have killed his father at a separate location.
Police said they had unconfirmed information from a social media account that the attack had been inspired by a similar incident in Russia, though did not provide further details.
They said the gunman was also suspected in the killing of a young man and his two-month-old daughter who were found dead in a forest on the outskirts of Prague on 15 December.
Of the 25 people wounded in the shooting, 10 were injured seriously, police said, adding that no officers had been hurt.
In a statement, Czech Prime Minister Petr Fiala said the country had been shocked by this "horrendous act".
"It is hard to find the words to express condemnation on the one hand and, on the other, the pain and sorrow that our entire society is feeling in these days before Christmas."
He said Saturday would be a day of mourning, adding that flags would be flown at half-mast on all public buildings and that a minute's silence would be observed at midday. Many sports and cultural events have been called off.