Really cool story, I thought it was a little short but it was definitely effective. I agree with the other reviewer about the multiple points of view, and wish that there could have been more character development, but still really enjoyed it.

The story is good. But I see some areas that could use improvement.
Starting with the beginning:
I'd like to see more back-story. What was happening before this? How did Gill get in this position? Who were the guys in his squad?
Also:
Exactly how high over the water is the bridge? If it's any more than 60 feet and he doesn't land feet first, Gill would probably have a few broken ribs, not just a numb side.If it's less than 30 then he should be fine (as in practically no injuries).
Some of his thoughts are a little wordy too. To quote specifically:
"I have to regroup on my squad" should be reduced. during most situations of high stress a person is likely to think or say things quickly. I'd suggest making this either something like "Gotta regroup" or making it something the narrator says. (this goes for a few of the other thoughts as well.)
I have trouble visualizing the scene. Why were there explosions going off around him? And what happened before all of this? Describe the scene better when he finally resurfaces. Is it jungle, rural area, or beach head? (I know you said it's a village, but amp the description up)
Also, where are all the other people in his squad after he falls? (just stuff to think about)
Take out the part with the sniper's point of view. Usually, when a situation like this comes along, you want it to be one of those "Holy crap!" moments. By giving the story two points of view you also break up the momentum of Gill's story. If you simply must have that POV change then give me some background on this kid. Just saying he's a random villager with a gun isn't enough.
Another suggestion has to do with history of WWII:
The M1A1 Thompson (as it was reffered to at the time) was put into service during WWII as a Submachine gun that fired a rifle calibur round. They had considerable recoil when combined with their high rate of fire. The M1A1 did not accept a drum-fed magazine. It was the later, smaller model (often reffered to as a tommy gun) that accepted both attatchments. The Thompsons used by the US troops in the Pacific were all clip-fed.
Artillery strikes (even ones today) are not that accurate. If someone called one in there would be quite a bit more explosions on the surrounding area and they would be huge (You would feel the vibrations). Maybe, a very lucky shot would have landed on the bridge (in which case ther would be huge pieces of debris flying everywhere and the bridge would be totalled.
Just to make this clear. I liked the story. But there are places you could improve for a better read.