tornado struck moore. nearly 250 troops are there now keeping the city safe. >> also searching for victims with the high-tech equipment. they've been working 'round-the-clock. and abc's mike boettcher is with them. >> reporter: they searched all night hoping for something, a murmur, a quiet call for help, and they searched all day. but as time passed, expectations changed. tiptoeing across a high wire made of debris, captain neil harvey, oklahoma national guard looked and listened hard for signs of life. but there were none. >> we are trying to find any shelters, possibly still, covered up. or anyone that is, trapped in place. >> reporter: to his partner, sergeant warren williams, equally agile traversing splintered houses, finding nothing exactly what he hoped for. what could be the best thing