The fire was located between the outer structure of the grill and the wall of the lower tray, basically between two sheets of metal. I was afraid that if I left it long enough to call 911, the entire space would fill up with flames and then the tank would have exploded for sure, as would our neighbor's car which was parked too close to the grill anyway. I think my moving the grill away from the car might have been what jostled the hose out of place, allowing the gas to leak into that space.

Plus, it would have been embarrassing to call the fire department ;-)