A Little White Lie
Instead of telling them what I saw and risking sounding like a madman, I told them there was a suspicious building in the woods and that I think it was being used for malicious activities, maybe even for occult rituals or human trafficking. I also added the fact that I had broken my leg trying to escape the scene and needed help.
That seemed to do the trick and I was assured that a team would be deployed immediately to investigate the building.