PRAGUE — The Czech Republic observed a minute’s silence at midday (11:00 GMT) to commemorate those killed in Thursday’s mass shooting at a Prague university.

Flags on official buildings were flown at half-mast to mark a day of national mourning.

Fourteen people were shot dead at the Faculty of Arts building of Charles University in the capital by a student who then killed himself.

Police are working to uncover the motive behind the attack.

It is one of the deadliest assaults by a lone gunman in Europe this century.

Those killed in Thursday’s attack included Lenka Hlavkova, head of the Institute of Musicology at the university.

Other victims were named as translator and Finnish literature expert Jan Dlask and student Lucie Spindlerova.

The shooting began at around 15:00 local time (14:00 GMT) at the Faculty of Arts building off Jan Palach Square in the center of the Czech capital.

The gunman opened fire in the corridors and classrooms of the building, before shooting himself as security forces closed in on him, police say.

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.”

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.”

The gunman is thought to have killed his father at a separate location. He is 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 Dec. 15.

The attack had one of the largest death tolls of any mass shooting by a lone gunman in Europe this century:

• Norway, July 2011 Anders Behring Breivik killed 77 people by planting a car bomb that killed eight at an Oslo government building and then shooting dead 69 more, most of them teenagers, at an island summer camp run by the ruling Labour Party’s youth wing.

• Germany, April 2002 Robert Steinhauser, 19, killed 16 people — 13 teachers, two pupils, and a policemen — at the Gutenberg Gymnasium secondary school in the city of Erfurt. He had been expelled from the school the previous autumn.

• Germany, March 2009 Tim Kretschmer, 17, killed 15 people in a shooting that began at his former school in the town of Winnenden, near Stuttgart. He shot dead nine students and three teachers at the school before going on to the nearby town of Wendlingen, where he shot another three passers-by.

• Switzerland, September 2001 Friedrich Leibacher entered the regional parliament building in the city of Zug dressed in a police uniform and shot dead 14 people and injured another 10.

• Serbia, April 2013 Ljubisa Bogdanovic shot dead thirteen people, including a two-year-old boy, and injured his wife in a village outside Belgrade. Bogdanovic was a military veteran who had fought with Serb forces in the Croatian War of Independence in the early 1990s.

Founded in 1347, Charles University is the oldest and largest university in the Czech Republic and one of the oldest such institutions in Europe. — BBC