Thousands are heading deep underground for a sound like no other. Good evening. Surging floodwaters have already trapped hundreds around boulder colorado and are threatening h more communities tonight. These pictures captured by a drone show what residents and rescuers are up against. The death toll is at least four. Officials caution they have yet to account for the whereabouts of many living in the flood zone potentially cut off by roads left impassable or washed away. An air lift operation is under way bringing some left stranded to safety. Through it all there have been dramatic, heartstopping rescues. Our team remains in place. Joe fryer leads off our coverage tonight from boulder. Joe . Good evening, lester. All the rain from the past week is still surging through rivers and creeks across colorado. And in some spots, thats creating more dangerous situations. No relief tonight from rapidly rising waters. As overflowing streams pour through even more parts of colorado. It is no dou