The allegations are that a gun belonging to another solider [sic], Master Cpl. Robbie Fisher, somehow went off in the vehicle, and the single shot hit Walsh.
This is a rifle, specifically the C-7 (right):
This is a Canadian-manufactured version of the M-16A2. it fires a bullet that is .223 inches/5.56 millimetres in diameter. It is carried by individual soldiers and fits inside just about any vehicle.
On the other hand, this is a gun [left].
Specifically, it is the M777 155 millimetre howitzer used by Canadian Forces in Afghanistan.
It is worked by a crew of several soldiers and simply doesn't fit inside any existing military vehicle.
While nits are being picked, the vehicle involved could not be a Jeep, as the CityNews story quoted above calls it. The same reference appears in the Canadian Press stories on the shooting incident as well.
The Canadian Forces has not used jeeps - i.e. the military version of the World War II light utility truck - since the early 1980s. Jeep refers to the trade-marked civilian vehicle.
Canadian Press has an excellent style guide and a caps and spelling guide that deals with just these pesky details.
Too bad more people writing news - including Canadian Press - don't use it.