SRL for [let off]: A convoy of police cars , ambulances and other rescue vehicles [let off] a long blast from their horns as the workers in orange jumpsuits stood quietly with eyes downcast , some removing their white hardhats .
ARG-0: A convoy of police cars , ambulances and other rescue vehicles | ARG-2: a long blast | ARG-1: from their horns | ARG-M-TMP: as the workers in orange jumpsuits stood quietly with eyes downcast , some removing their white hardhats