What should I do after telling police of my ault?

Im 17 years old and was aulted by another 17 year old who punched me in the face without reason and I did not retaliate, I went into a grocery store and called 911. I live in WA state, and I was wondering - what do I do after telling the police who did it and providing witnesses names/numbers etc. How do I know action has been taken? Do I press charges? What should I do?