Police have not released the identities of the victims. Charles University’s Institute of Music Sciences confirmed in a Facebook post that its head, Lenka Hlávková, was among the dead.

Citing unconfirmed information from social media, Czech police head Martin Vondrášek said the gunman was inspired by a “similar case that happened in Russia.” Earlier this month, a Russian teen named Alina Afanaskina shot and killed a fellow student before shooting herself in the city of Bryansk. Czech Interior Minister Vít Rakušan said investigators do not suspect a link to any extremist ideology or groups, or international terrorism.

The shooting is the fourth major mass-killing by a single gunman this year in Europe, where such attacks are considered shocking and rare. In May, two separate attacks in Serbia within the span of a week shocked the nation and led the president to pledge gun reforms and a “total disarmament” of the country. In March, a gunman killed six people at a Jehovah’s Witness hall in Hamburg.

“We always thought that this was a thing that did not concern us. Now it turns out that, unfortunately, our world is also changing and the problem of the individual shooter is emerging here as well,” Prague Mayor Bohuslav Svoboda said on Czech Television, according to Reuters.

Authorities received a tip-off earlier on Thursday that the suspect, who had no criminal record, had left for Prague from his town in the nearby Kladno region “saying he wanted to kill himself.” His father was found dead soon after.

Following the tip, police searched a faculty of arts building where the gunman was expected to show up for a lecture. Instead, he went to the faculty’s main building nearby where shots were fired at around 3 p.m. local time on Thursday. The gunman had a “huge arsenal of weapons and ammunition,” police said.

Videos posted by witnesses on social media showed locals and tourists running from the area. The building where the shooting took place is in Jan Palach Square, a busy tourist area in Prague’s Old Town, named after a Czech student who died of self-immolation protesting Soviet occupation in 1968. While students and university staff barricaded themselves into rooms, others were seen fleeing through windows before precariously sheltering on the edges of the building.

Video released by Czech police Friday shows chaotic scenes of people and vehicles fleeing the square as police arrive and begin entering the building armed with assault rifles. The video shows police breaking open doors and clearing classrooms, with students lying on the floor with their hands on their heads.

In one classroom, pairs of police officers can be seen treating wounded people, handing each other bandages and tourniquets. The wounded people are blurred out in the video. Another clip shows police carrying a person across the square on a stretcher. The person can be heard whimpering in pain.

In an image evocative of school shooting scenes in the U.S., a large group of students is escorted around the outside of a building with their hands in the air. Police tell people in mass-shootings to do so as they work to identify who is the shooter and who isn’t.

Petr Matejcek, a police official, said the gunman shot himself on a balcony of the university, the Associated Press reported. The videos released by police show a blurred-out body lying on a balcony.

Late Thursday police said they believe the gunman also killed a young man and his 2-month-old daughter in a stroller in a forest on the outskirts of Prague on Dec. 15, a case that has gripped the country over the last week.

Early Friday, as people lit candles at an impromptu vigil, the government declared a national day of mourning on Dec. 23. Flags on official buildings will be flown at half-staff and a minute’s silence will be observed at noon.

Police stepped up security at schools and other “soft targets” Friday as a preventive measure, while Charles University canceled all lectures and events.

The shooting led to an outpouring of condolences from world leaders. “The president and the first lady are praying for the families who lost loved ones and everyone else who has been affected by this senseless act of violence,” White House press secretary Karine Jean-Pierre told reporters. “Federal authorities are in touch with Czech authorities as they investigate this incident.”

Despite having more permissive gun laws than most of its European neighbors — even allowing concealed carry with a permit — the Czech Republic requires citizens to take strict tests before being able to obtain weapons.

Mass killings are rare but have happened before. In 2019, a gunman killed six people at a Czech hospital in the city of Ostrava before turning the gun on himself. Four years earlier, a gunman shot eight people and himself in the town of Uherský Brod.

De Vynck reported from Brussels.