Relief groups such as Mercy Corps have been sending teams of emergency response experts to assess needs and coordinate relief efforts. Mercy Corps communications director Caitlin Carlson says the most immediate needs are for food, clean water, sanitation services and shelter.
"People are afraid to go back into their homes - if they are still standing. They don't know if there will be aftershocks that knock them down. Shelter is one of the biggest needs."
Americans seeking information about family members in Haiti can call the U.S. State Department in Washington, D.C., toll-free at 1 888-407-4747. An estimated 40,000 Americans live in Haiti.
Carlson says relief workers will take very little with them in terms of supplies when heading to Haiti - with the goal of purchasing as much as possible locally.
"In the aftermath of a disaster, economies shut down, so spending a little money to buy these supplies not only helps the people getting the supplies, but it helps the people who are selling the supplies."
Mercy Corps expects the Haitian government to let its emergency response team into the country quickly to assist with the relief efforts, Carlson says. The group will post updates, and is taking donations, at www.MercyCorps.org.