(QHA) -

Ukrainian President Petro Poroshenko has declared January 15 a day of mourning as a rocket hit a passenger bus, killing 12 civilians in Volnovakha, east Ukraine, Jan 13.

Poroshenko said on January 14 after meeting with regional governors in Kyiv that the order commemorates "all those, who died from terrorists' actions, and first of all, those 12 civilians, who were killed at military checkpoint near the town of Volnovakha" in Ukraine's eastern region of Donetsk.

The separatist, self-proclaimed Donetsk People's Republic denied responsibility, saying the government checkpoint was "beyond our artillery's range."

The UN Security Council strongly condemned the attack on January 14.