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
Ukrainian police officers have been pictured carrying sniper rifles near Independence Square in Kiev.
Photographers for the Kyiv Post, an English-language newspaper in the capital, took the photographs amid continuing violence between police and protesters.
The number of fatalities has increased, while a medic for protesters has claimed that many were killed by gunfire.
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.