Updated

Teams from across the U.S. government, including the Defense, State and Homeland Security Departments, are coordinating efforts to assist victims of the powerful earthquake that struck Haiti Tuesday.

President Barack Obama told members of his national security staff late Tuesday that he expects "an aggressive, coordinated effort." Earlier, Obama said his thoughts and prayers were with the people of Haiti and said the U.S. stood ready to help the impoverished Caribbean nation.

SLIDESHOW: Devastation in Haiti

VIDEO: Witness Describes Earthquake

The 7.0-magnitude earthquake caused thousands of buildings to collapse in Haiti's capital, Port-au-Prince, trapping untold numbers in tons of rubble. While estimating the number of casualties was impossible, State Department spokesman P.J. Crowley said, "Clearly, there's going to be serious loss of life in this."

Late Tuesday, deputy national security adviser Tom Donilon convened a meeting in the White House with senior representatives from the State Department, the U.S. Agency for International Development, the U.S. Mission to the United Nations, the Defense Department, U.S. Southern Command, the Joint Chiefs of Staff, the Homeland Security Department, the Coast Guard, and national security and White House staff to coordinate the government-wide response.

USAID said it was sending a disaster assistance response team and had activated its partners, the Fairfax County (Va.) Urban Search and Rescue Team and the Los Angeles County Search and Rescue Team.

Coast Guard officials in Miami mobilized cutters and aircraft to positions near Haiti to offer humanitarian assistance.

The State Department set up a toll-free number to call for information about family members in Haiti: 1-888-407-4747. The department said some callers may receive a recording because of heavy volume of calls.

The State Department has also set up links on its Web site to facilitate donations to disaster relief agencies.