Answer:
The referee must send the player off for violent conduct and write up what happened in the game report. If the referee feels at any moment that his safety is in continuing jeopardy, the game must be abandoned as well.
Referee associations strongly recommend that the referee file assault charges with both the league, national referee association, and local law enforcement. Regardless whether the referee does this, a time-limited or lifetime ban could be given by the league and/or national association.