I would certainly disagree with the advice to wet down personal clothing garments as well, but wetting down a radiant barrier held out at arms length between a couple of people (or tied to a couple of poles at each corner) could provide a useful radiant heat barrier which could protect a group of people from the radiant heat source. Wetting down the blanket would increase the time it takes to reach its flash point temperature before it catches fire.

Even taking a door of its hinges and using this a radiant heat barrier could be improvised if time allowed.