At least 15 people have been killed in a shooting in central Prague, according to Czech emergency services.
The gunman is among the dead and at least 25 others have been wounded - with 10 seriously injured.
The body of the gunman - a 24-year-old student at Charles University in Prague - was discovered in the university's philosophy building, according to officials.
Police said the gunman's father was also found dead at a property in Hostoun, a village to the west of the Czech capital, earlier today.
Officers are still sweeping the area, including the building's balconies, for possible explosives.
Tánaiste and Foreign Affairs Minister Micheál Martin said he was 'shocked' by the tragedy.
Shocked by the terrible tragedy today in Prague. I offer my sympathies to the families of the victims and my condolences to the people and Government of the Czech Republic. Ireland stands in solidary with you at this time.
— Micheál Martin (@MichealMartinTD) December 21, 2023
Czech Interior Minister Vit Rakusan earlier confirmed to media that the gunman had died.
"According to preliminary information, the shooter himself should be dead, there are dead and wounded on site, I will not speculate now about the final number," he said on Czech television earlier.
In a post on X, he added: "Please follow the instructions of the police, the situation is serious.
"I am going straight to the place to familiarise myself with the situation."
Czech Prime Minister Petr Fiala also cancelled his scheduled events to travel to Prague.
He said he was "shocked" by what happened and offered his condolences to the relatives of the victims.
The incident place took place in the area of Jan Palach Square, in Prague's Old Town district.
Irish citizens were asked to follow the advice of local authorities.
There have been reports of a shooting in the centre of Prague at the Faculty of Arts, Charles University. We ask all Irish citizens to follow the advice of local authorities. Please contact the Embassy on +420 257 011 280 with any requests for consular assistance.
— Irish Embassy Prague (@IrlEmbPrague) December 21, 2023
The suspect - who has not yet been named by police - legally owned several guns, and carried out what Prague police president Martin Vondrasek described as a "well-thought-out" and "horrible act".
Mr Vondrasek said police had evacuated another university building - where the student had been due to attend a lecture on Thursday - prior to the shooting.
Members of the public were advised to leave the area, home to The Philosophical Faculty of Charles University and the Academy of Arts, Architecture, and Design.
An email sent to staff at the Faculty of Arts of Charles University while the incident was ongoing said a shooter was in one of the buildings and urged staff to "stay put", according to Reuters.
"Don't go anywhere, if you're in the offices, lock them and place furniture in front of the door, turn off the lights," the email said, according to the news agency.
One X user earlier posted a photo of a group of students, hiding crouched on a ledge of the building.
Prague Mayor Bohuslav Svoboda said both The Philosophical Faculty of Charles University and the Academy of Arts, Architecture, and Design, were evacuated.
Petr Nedoma, director of the Rudolfinum Gallery at a concert hall across Palach Square, told Czech TV he saw the gunman.
"I saw a young person on the gallery who had some weapon in his hand, like an automatic weapon, and shooting toward the Manes Bridge, repeatedly, with some interruptions," he said.
He said he saw the gunman put his hands up before throwing the weapon down on the street, where it landed on a pedestrian crossing.
European Commission President Ursula von der Leyen said she was "shocked by the senseless violence of the shooting".
Shocked by the senseless violence of the shooting that claimed several lives today in Prague.
I express my deepest condolences to the families of the victims and to the Czech people as a whole.
We stand and mourn with you.— Ursula von der Leyen (@vonderleyen) December 21, 2023
White House Press Secretary Karine Jean-Pierre said the US stood "ready to provide additional support as needed" to Czech authorities.
