A shooter killed at least 14 people and wounded 25 others at a university in Prague on Thursday in the deadliest mass shooting the Czech Republic has seen in decades.

Authorities believe the gunman, a 24-year-old man, died by suicide, Czech Police Chief Martin Vondrášek said Thursday evening, but added it had not yet been confirmed. The gunman, who police said was a student of the Faculty of Arts at Charles University, has not been formally identified because of the severity of his injuries, the chief said. Police have not named him.

Authorities are still investigating a motive in the rampage, which took place at the Faculty of Arts building of Charles University, in the center of the capital city. The area is popular with tourists and close to major attractions, just across the Vltava River from Prague Castle.

The shooter traveled to Prague from his hometown village of Hostouň, the police chief said.

As the violence broke out, some students locked themselves in classrooms to avoid the gunfire, police said. A picture shared on social media showed several people hiding on an outside ledge high up in a building.

The university was holding classes on Thursday and was due to go on Christmas break on December 23, according to a schedule on the university’s website.

Graduate student Jakob Weizman told CNN he was in a classroom with his professor when they heard what sounded like gunshots and screams. The 25-year-old locked the door and with his professor, began pushing furniture against it to create a barricade.

“After I made the barricade and locked the door, I hid under the desk and I was preparing myself for anything that could happen,” Weizman said. “I did not know if (the shooter) was going to come through the door or from the window.”

He took down the barricade only when police arrived, he said. Authorities escorted him down and out of the building, the student told CNN he saw blood on each floor. “It was very traumatizing,” he said.

In a later news conference Thursday night, Vondrášek revised the number of people killed to 14, after previously saying 15 people had died. Of the 25 people injured, 10 were in serious condition, the police chief said.

The next update from authorities is expected Friday morning.

Shooter may be linked to other killings

The police chief said authorities had information about the shooter before the university killings, saying police received a tip he was traveling to Prague with the intention to take his own life.

Shortly afterward, they received information a deceased man was found in Hostouň, a town around 13 miles (21 km) west of Prague. The man is believed to be the shooter’s father.

Vondrášek said the police were aware the shooter had a lecture at 2 p.m. CET and evacuated the building where the lecture was meant to take place. But authorities then received a call about a shooting in a different building, according to the police chief.

Czech authorities are also working on a theory the gunman is connected to a double homicide in Klanovice, a Prague suburb, last week, Vondrášek said. Authorities are still conducting a thorough investigation in that case, the chief added.

The shooter had a gun permit and owned several weapons, Vondrášek said.

Country declares day of mourning

The Czech Republic will observe a day of mourning Saturday for those killed, country officials announced at a joint news conference late Thursday.

“I want to express my deep sadness and also helpless anger over the loss of so many young lives,” Czech President Petr Pavel said.

The massacre is “the most tragic incident in the history of the Czech Republic,” he added.

Flags will be flown at half-staff during the day of mourning and a minute of silence will be held nationwide at noon Saturday. Bells across the country will also toll for the victims of the attack, Czech Prime Minister Petr Fiala said.

Earlier, Fiala said authorities believe the shooting was a lone incident and there was no remaining danger. Interior Minister Vít Rakušan said the shooting was not an act of terrorism.

Charles University said it tightened its security measures “with immediate effect” and canceled events at the university on Thursday and Friday. In a statement posted on X, it also “called for an adequate and sensitive approach to [Friday’s] possible exams or credit examinations.”

“We now ask everyone to try to remain calm and composed, and we again extend our condolences to all those whose hearts have been broken by the loss of loved ones,” the university said.

The Czech Republic has relatively liberal gun laws compared to the rest of the European Union, but gun attacks are rare. To obtain a gun legally, a person needs an official firearm license, which requires a medical examination, a weapon proficiency exam and no previous criminal record.

According to official police statistics, more than 300,000 people have a legal permit to own a gun. As of 2022, almost 1 million legally owned weapons were officially registered in the Czech Republic.

In December 2019, a 42-year-old man killed six people at a hospital waiting room in Ostrava in the east of the country before shooting himself.

And in 2015 a man killed eight people in a shooting at a restaurant in Uhersky Brod before killing himself.