A 30-foot deep "surge of water, mud, rocks and debris" dissipated before reaching the outskirts of Boulder, Colo., emergency officials said early Friday.
Area residents were told to move to higher ground after a witness spotted the surge -- which included cars -- heading down Fourmile Creek toward Boulder Creek around 11:10 p.m. local time (1:10 a.m. ET), according to the Boulder Office of Emergency Management. The National Weather Service had initially characterized the incident as "potentially life threatening."