By IAN AUSTEN and VJOSA ISAI A grass fire on a military base in Alberta, Canada, on Saturday was whipped by the wind at such remarkable speed, more than half a mile a minute, that it overwhelmed soldiers in a combat exercise, killing four of them and injuring 39 others, Canadian authorities said Sunday. At least 19 were in critical condition. The fatal accident occurred at Canadian Forces Base Wainwright, one of the country’s largest army bases, and involved troops training with live…
