Late Thursday afternoon, Preval said 7,000 people were reportedly buried in one common grave. Makeshift morgues have been set up in churches, and some people have begun collecting identification cards off corpses to try to compile a master list of the dead.
There were roughly 45,000 Americans living in Haiti at the time of the earthquake.
The State Department late Thursday afternoon confirmed one American death -- 57-year-old Victoria DeLong, a cultural affairs officer at the U.S. Embassy in Port-au-Prince who had been stationed there since February 2009 and joined the State Department in 1983.
The U.S. government was looking into three possible additional American fatalities, but could only confirm DeLong had died.
The Hotel Montana -- where Chand and Santos were rescued, and where a rescue effort continued -- is where the U.N. housed much of its staff in Haiti.
An American named Rudy Bennet has been trapped in the Hotel Montana and has been texting relatives back in the U.S.
The earthquake that struck Tuesday may have claimed 45,000 to 50,000 lives, according to Haiti's Red Cross.
"No one knows with precision. No one can confirm a figure," Victor Jackson, an assistant national coordinator with Haiti's Red Cross, told Reuters.
For full Haiti Earthquake coverage watch World News With Diane Sawyer this evening. Check your local listing for times.
"It will take hours, in many cases days to get all of the rescue teams and resources on the ground in Haiti to assist with the rescue effort," President Obama said in a televised statement from the White House this morning.
Flanked by Vice President Biden and Secretary of State Hillary Clinton, Obama said that leaders from his national security team must make Haiti "a top priority."
Obama earlier had pledged initial support of $100 million towards the relief efforts. He has also asked former presidents George W. Bush and Bill Clinton to lead fundraising efforts.
U.S. corporations have pledged nearly $15 million, an amount that is sure to increase in the coming days.
Obama outlined steps successfully taken: The aircraft carrier USS Carl Vinson will arrive on Friday with 19 helicopters. Members of the 82nd Airborne have hit the ground in Haiti. Three aircraft landed Thursday with search and rescue teams. Five additional planes were scheduled to land Thursday evening with further rescue teams, dogs, medical supplies and pallets. Several Coast Guard cutters are providing basic supplies and technical equipment. Three U.S. ships offering hospital services and medical support were scheduled to arrive in Haiti on Jan. 15, 18 and 22.
Not only military ships are involved. Cruise ships are joining the rescue effort as well. The Royal Caribbean International cruise liner announced today that relief supplies such as rice, beans, water, dried milk and canned goods have been loaded onto the Independence of the Seas, which had already been scheduled to dock at Royal Caribbean's port on Friday in the north of Haiti in Labadee. There were no reports of damage at the port. Relief supplies were to be distributed by "Food for the Poor."
The needs are overwhelming. Thousands are believed to be trapped in collapsed buildings after the 7.0 magnitude earthquake, with an additional three million Haitians in need of aid.