Does a 777 carry any form of stretcher? My research suggests that it doesn't.
Can you imagine how you'd scavenge a 777 to make a few stretchers? Are there some long "rods" that could be easily removed? It could be a flat panel about 6' long that 4 people could carry. Basic tools are available (what you'd expect to find in a flight technician's tool bag/bog). It has to be relatively straightforward to do, it can't require all day to do it. There are trees a few miles away from the crash site, so it might be easiest to cut branches and fashion something.