I think @jaytkay probably got closest to the right answer. Without knowing more about the photographer’s technique it’s hard to say. (@jeffgoldblumsprivatefacilities could also be correct, and it could be a camera artifact, which would be easier to determine if we had more samples of photographs taken with the same equipment.)
My own expectation, like @jaytkay, is that the shot was a timed exposure in order to capture one or more lightning bolts in the same image. In that case, knowing how long the exposure was would allow you to calculate the distance traveled for whatever is making those lines. That’s why I don’t think they are meteorites or anything traveling with anywhere near that speed.
What I’m seeing is two faint lines, one longer one bisected by the bright bolt of lightning, and one emanating from (and superimposed on the left edge of) the ejecta cloud and traveling down and to the left in the photo. The lines do appear to be parallel.
If one considers that the objects making those tracks or lines were not traveling purely perpendicular to the point of view of the camera, but on trajectories that took them toward or away from the photographer as well as laterally, then the speeds would have been much greater than if they had a lateral motion only in a plane perpendicular to the photographer’s view.
In fact, since there’s no gravitational ‘arc’ to the lines (and if we assume they aren’t artifacts of the lens), I would estimate that these are objects from within the ejecta moving at a very high rate of speed away from the photographer.
With only this photo and no other explanation of technique it’s really impossible to say more, I think.