Ukrainian troops conducting house-to-house fighting engage Russian forces when one of their guys is hit in the face by a piece of shrapnel. The injured Ukrainian then returns fire, ignoring his own injuries in favor of attempting to hit the guy who caused the light injury to his face.

The injury occurs to the Ukrainian Soldier just seconds before the cameraman starts filming. You can hear him in the stairwell having an obscenity filled rant as soon as the camera starts, just before he pops the corner and starts engaging down the long axis of the building.

It's unclear without a translation if the Ukrainians are fighting with Russian troops inside of the building they are in, or if there is an exit from the building at the end of the hallway that the Ukrainian is engaging out of that would indicate he is firing towards another building or position.