You're walking home, late at night. Another person of the same sex as you approaches you.

They attempt to interact with you in an aggressive manner. When you try to warn them off, they respond with increased hostility. Suddenly, they punch you. You attempt to ward off further blows, but only end up pushing them.

When you recover, you see your assailant has fallen backwards and is no longer conscious. A quick check indicates that the assailant is no longer breathing.

No one else is around. The area where you are isn't overlooked by any buildings. Do you attempt to carry out CPR and contact emergency services? What do you tell them if you do?