Mas maganda kung may mga police within the immediate vicinity, pero kung wala, pictures will do. If both parties are amenable to filing a police report, it's better.

When I was involved in an accident one time, walang pulis, ni traffic enforcer. And neither of us was able to take a picture of the scene (we were only able to take pictures of our own damages a few days later). I had been willing to file a police report pero the other party declined, nagmamadali daw siya. Kahit notarized affidavit, wala kami. When I referred it to my insurance company for the claims, they just asked us to provide a few personal details, plus a short description of the circumstances surrounding the accident, signed by me and the other party.