It was a beautiful day to be on the track and there was not very many people. Unfortunately, 4 people from various groups went down at the same location on turn 9 throughout the day, I was the one in advanced that went down. I left after that but in the ambulance ride, you could hear them talking on the radio asking if anyone saw any reason why everyone was going down. Not sure if they got it figured out after I left. Felt like oil or antifreeze because there was no warning , I just initiated the turn, not even getting my knee down, and in a flash my front end was down and I was sliding. Not hurt and bike is fine.