Explosions were heard in the Ukrainian capital and other major cities following Vladimir Putin's announcement that a military operation had begun.
Photos and video showed Ukrainians driving out of Kiev Thursday morning, as air raid sirens wailed across the capital, the Daily Mail reported.
Many were either heading for the exits or lining up in lengthy queues for gasoline, with some stopping at ATMs beforehand.
Intense lines were also seen at Kiev's Metro station with people attempting to get onto trains to flee the city. Some were just heading into the station to take refuge.
The Russian president announced the action during a televised address early on Thursday morning, saying the move was a response to threats from Ukraine.
He said Russia doesn't have a goal to occupy Ukraine. Putin says the responsibility for bloodshed lies with the Ukrainian "regime".
Putin also warned other countries that any attempt to interfere with the Russian action will lead to "consequences they have never seen".