Check out this interesting footage of the hand grenade attack against the security forces guarding the Rada in Kiev:
I would like to add a couple of comments here:
First, notice that the guy throwing the grenade is not wearing any combat fatigues or Right Sector or Svoboda uniform.Second, he carefully checks the movement of another rioter to his right who is picking up a smoke grenade to toss it at the cops before throwing his own, real, combat grenade. Pretty skilled move. Lastly, he appears to be alone and his action is not part of any coordinated attack but rather an attempt to get some blood flowing.