The Oakland PD says it's on the hunt for the person who allegedly pushed a fan off the 2nd deck at Oracle Arena during Game 7 Sunday night ... in an incident that left the victim in critical condition.
Cops say they believe the victim and the suspect were fighting in the stands -- unclear why -- with a man in his early 20s getting shoved over the rail ... and suffering serious injuries in the process.
One witness tweeted that she saw blood coming out of the victim's ears.
The man was transported to the hospital -- and officials say he's now in critical but stable condition.
Cops say they are looking through surveillance footage and talking to witnesses to try to find the suspect. So far, no arrests have been made.