Ukraine bus attack kills 12 as airport battle worsens

Ukraine's President Petro Poroshenko is seen as he makes his address to the nation in Kiev, in this January 13, 2015 handout photo provided by the Ukrainian Presidential Press Service. REUTERS/Ukrainian Presidential Press Service/Mykola Lazarenko/Handout via Reuters

KIEV (Reuters) - A passenger bus came under heavy fire in eastern Ukraine, killing 12 people, Ukrainian authorities said, and fighting intensified around the international airport in the city of Donetsk as separatists tried to oust government forces.

The latest violence flared on Tuesday after Russia, Ukraine, France and Germany scrapped plans for a summit in Kazakhstan this week because of the failure to implement a four-month-old ceasefire agreement.