Ukraine crisis: Central government's authority is collapsing

(CNN) – When the Ukrainian president said he had lost control of eastern Ukraine, he wasn't kidding.

Riot police fired tear gas and stun grenades at protesters Thursday, but they were no match for the sticks and stones of pro-Russian protesters who just took over another government building near the border.

If that wasn't embarrassing enough, in a phone call with German Chancellor Angela Merkel, Russian President Vladimir Putin demanded the Ukrainians pull back their troops from the eastern region of their own country.

CNN's Nick Paton Walsh reports.