A 24-year-old Czech student fatally shot his father, then killed 14 people and wounded 25 others at his Prague university on Thursday before possibly killing himself, police said, marking the country's worst-ever mass shooting.

The government declared a day of mourning across the central European country for Dec. 23 to remember the victims, decided at a special cabinet meeting with President Petr Pavel.

"I would express my great sadness along with helpless anger at the unnecessary loss of so many young lives," Pavel said.