Ukraine's acting president has warned Russia that troop movements outside its naval base in Crimea would be seen as an "act of aggression". Armed men seized regional government headquarters and parliament and the Russian flag is flying from buildings
Ukraine's parliamentary speaker was quoted on Saturday as saying President Viktor Yanukovich had tried to board a plane to Russia but had been prevented from doing so and was now in the Donetsk region.
"He tried to get on a plane to Russia but border officials stopped him," Interfax news agency quoted Oleksander Turchynov, an opponent of Yanukovich, as saying.
Ukraine's interim President has expressed concerns about signs of separatism as opposition in Russian-speaking regions grows.
Hundreds of Ukrainians and journalists flocked to the presidential palace, as reports emerged that President Yanukovich had left the city.
Vitali Klitschko was met with boos from anti-government protesters, as he attempted to convince them a peace deal is best course of action.