AMNA NAWAZ: Welcome to the "NewsHour."

One of Europe's most majestic capitals was shattered today by gunfire.

A shooter at a university in Prague killed at least 14 people and wounded at least 25.

The government of the Czech Republic has declared Saturday a day of national mourning.

Prague is on high alert after the mass shooting at a Charles University building downtown; 43-year-old Ivo Havranek was an eyewitness.

IVO HAVRANEK, Witness: It was a couple of bangs.

I didn't even realize it's a shooting.

Then, suddenly, there were students and teachers running out of the building.

AMNA NAWAZ: Havranek was downtown during the shooting and filmed this video of police rushing to secure the scene and people hiding from the gunmen on the rooftop.

Police say the suspect was a 24-year-old who had expressed suicidal thoughts.

He killed his father in the Kladno region outside the capital before going to Prague to continue the violence.

He opened fire on the philosophy department, where he was a student.

The shooter has not been named but police say he was killed.

The motive is unknown, but police said there was no indication that this attack was international terrorism.

MARTIN VONDRASEK, Czech Republic Police Chief: We want to ask for some understanding because the investigation is ongoing.

At the moment, we do not have final information and we have not even started identifying those who were shot, because first the area simply has to be clean for us and safe for others.

AMNA NAWAZ: This is the worst mass shooting in the history of the Czech Republic.

PETR FIALA, Czech Republic Prime Minister (through translator): We are doing everything we can to provide assistance to the injured, their families and the families of the victims.

Dear fellow citizens, let us now think of those who have lost loved ones and for whom this Christmas will be unimaginably sad.

Let us share their grief and their pain.

AMNA NAWAZ: As night fell, authorities searched the area for any further threats.

Tensions remain high, as Christmastime is one of the city's busiest tourist seasons.