With prayer and the somber ringing of church bells, residents in Mississippi and Louisiana gathered today to mark the 10th anniversary of the day that Hurricane Katrina slammed into their states. At New Orleans' memorial to the unclaimed and unidentified dead, Mayor Mitch Landrieu spoke of the dark days after the storm. "We saved each other," the mayor said. "New Orleans will be unbowed and unbroken." The hurricane's force and flooding caused more than 1,800 deaths and roughly $151 billion in damage. (Here are 10 great reads about Katrina.)