Truck without warning, suddenly stopped and I was on one of the busiest streets in Los Angeles at an intersection, blocking a large amount of traffic and too dangerous to get out due to cars rapidly passing. Called Rivian support and they said it would take. two hours to get a tow truck to me even though AAA was only 20 min away, they would not call AAA. I was at risk of being rear ended. Fire department came and was able to move car to side of road. Rivian gave no assistance. Engine light came on and said call tow truck and do not drive, red lights, manual said it was dangerous.