Bodies line the streets of Haiti following Tuesday's massive earthquake that one seismologist called "the big one." Officials fear hundreds of thousands of people could be dead.
The Caribbean nation was devastated by the 7.0 earthquake -- the president's palace, the cathedral, the main prison and whole neighborhoods were flattened.
"Parliament has collapsed. The tax office has collapsed. Schools have collapsed. Hospitals have collapsed," Haitian President Rene Preval told the Miami Herald. "There are a lot of schools that have a lot of dead people in them."
Sen. Youri Latortue told the Associated Press that 500,000 could be dead, although he acknowledged that nobody really knows anything just yet.
The head of the U.N. peacekeeping mission is missing and the Roman Catholic archbishop of Port-au-Prince is dead.
"The cathedral, the archbishop's office, all the big churches, the seminaries have been reduced to rubble," Archbishop Bernardito Auza, the apostolic envoy to Haiti, told the Vatican news agency FIDES.
The United States is among scores of nations sending help to Haiti. President Obama promised an all-out rescue and humanitarian effort. "We have to be there for them in their hour of need," Obama said.
The U.S. Navy aircraft carrier, USS Carl Vinson, is en route and expected to arrive off the coast of Haiti Thursday. Additional U.S. Navy ships are sailing to Haiti, a statement from the U.S. Southern Command said.
An estimated 40,000-45,000 Americans live in Haiti, and the U.S. Embassy had no confirmed reports of deaths among its citizens. All but one American employed by the embassy has been accounted for, State Department officials said.
The International Red Cross said the situation is dire -- a third of Haiti's 9 million people will need emergency aid.
A seismologist at the British Geological Survey told TIME magazine that this was the so-called "big one" for this particular fault line. Roger Musson said, "This was the big one. The fault has been more or less locked for 200 years. Seismologists were unsure as to whether it would produce one big one or several smaller ones. We seem to have the answer."
Watch video of the devastation here: