PRAGUE — An armed man opened fire in a university building in downtown Prague on Thursday, killing at least 15 people and sowing widespread panic with one of the Czech Republic’s worst mass shootings of its kind, police and the city’s rescue service said.

The bloodshed took place in the philosophy department building of Charles University, where the shooter was a student, Prague Police Chief Martin Vondrasek said. He has not been named publicly.

Police gave no details about the victims or a possible motive for the shooting at the building located near the Vltava River in Jan Palach Square. Czech Interior Minister Vit Rakusan said investigators do not suspect a link to any extemist ideology or groups.

Pavel Nedoma, the director of the nearby Rudolfinum Gallery, said he saw from a window a person standing on a balcony of the building and shooting a gun.

Police said they were still searching the area, including the balcony, for possible explosives. The building was evacuated, Prague Mayor Bohuslav Svoboda said.

The building forms part of the square and faces a bridge across the river with a view of Prague Castle, the seat of the Czech presidency. President Petr Pavel said he was “shocked” by what happened and offered his condolences to the relatives of the victims.

Where tourists, students and others would normally be enjoying the view of the iconic monument instead reflected chaos and terror on Thursday afternoon. Police vehicles and ambulances sped across the bridge with their sirens wailing to each the empty square, which was sealed off by officers.

Some video footage from the scene showed people being evacuated from the building and others trying to hide by a wall.