It started as a rally to demand Ukrainian President Viktor Yanukovich move forward on a key partnership agreement with the European Union.
It wasn't long before protesters were clashing with riot police outside government headquarters in the capitol, Kiev.
Many in this crowd say the government's decision to not sign the proposed pact with the EU --- is a step in the wrong direction.
Opposition politician Vitaly Klitschko.
SOUNDBITE: Opposition politician Vitaly Klitschko saying:
"We will not tolerate what (President Viktor) Yanukovich has done, what the leadership and the government of (Prime Minister Mykola) Azarov have done who stopped EU integration. We will all fight in order for the association agreement to be signed."
The agreement with the EU would have marked a historic swing westward and away from Russia -- a break which prompted the Kremlin to threaten retaliation and a possible cutoff to strategic supplies of gas.
By day's end, oppos
