WHILE DISMANTLING A WATER TOWER, AN IRON WORKER WAS SERIOUSLY INJURED & PINNED AS HE WAS REMOVING A PORTION OF A WATER TOWER LEG (APRX 92 FT AGL). THE HELICOPTER PLT RESPONDED TO THE EMERGENCY. THE ACFT WAS EQUIPPED WITH A MAKE-SHIFT SLING LINE TO RETRIEVE THE INJURED IRON WORKER. THE IRON WORKER DIED, BUT THE HELICOPTER PLT VOLUNTEERED TO CONTINUE WITH THE MISSION. THE PLT WAS NOT FAMILIAR WITH THIS TYPE OF OPERATION, BUT A PARAMEDIC WAS ON BOARD TO ASSIST. THE PARAMEDIC WAS NOT FAMILIAR WITH HELICOPTER OPERATIONS. SVRL QUARTZ HALOGEN LGTS WERE USED TO ILLUMINATE THE 4 WATER TOWER LEGS. AT THE PLT'S REQUEST, ALL BUT 1 WERE TURNED OFF TO KEEP FROM BLINDING THE PLT AS HE HOVERED OVER THE STRUCTURE AT NGT. THERE WAS NO DIRECT RADIO COMM BETWEEN THE PLT & GROUND PSNL, BUT THE PARAMEDIC WAS IN CONTACT WITH GROUND PSNL. WHILE HOVERING, THE HELICOPTER MOVED SLOWLY BACK TOWARD A LEG OF THE STRUCTURE. GROUND PSNL TRIED TO WARN THE PLT, BUT THE HELICOPTER HIT A WATER TOWER LEG, THEN CRASHED & BURNED.