Sentence:  From the east to the west coast of the Korean peninsula was a strip of land in which fear filled men were at that same moment furtively crawling through the night , sitting in sweaty anticipation of any movement or sound , or shouting amidst confused rifle <WSD>flashes</WSD> and muzzle blasts . 
Meaning of the word marked with <WSD> tags:  a sudden intense burst of radiant energy