Nato's Secretary General Anders Fogh Rasmussen says he is "extremely concerned" after gunmen stormed government buildings in Crimea. The group raised a Russian flag and with it raised fears of a regional conflict.
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.