Getty ImagesAmerican leader Barack Obama has phoned Russian president Vladimir Putin to urge him to help stop protesters in eastern Ukraine.
Pro-Russian groups have taken over more government buildings, despite a warning of military action from Ukraine.
Putin says Russia hasn't been interfering.
Protests by people who want Ukraine to stay as one have also taken place.
To enjoy the CBBC Newsround website at its best you will need to have JavaScript turned on.
A crisis meeting between Ukraine, Russia and the West is due to take place on Thursday.
