The United States government is mobilizing cash and disaster-response teams to help people in the tsunami-stricken nations of Asia as they recover from the tragedy that caused at least 23,700 deaths in eight countries on Sunday.

The African nation of Somalia also reported 100 deaths as a result of killer waves that crossed the Indian Ocean following an earthquake Sunday morning.

Secretary of State Colin Powell told reporters Monday that $400,000 has gone to India, Indonesia, the Maldives and Sri Lanka (search) already, and about $4 million is in the works to be given to the International Red Cross and Red Crescent Societies (search). The Red Cross had asked for $6.6 million.

U.S. Agency for International Development (search) assistant administrator Ed Fox added that the U.S. aid package could reach as much as $15 million once formal requests are in from governments and recommendations are made from disaster-assistance response teams on the ground.

USAID, the key American agency that provides assistance to countries recovering from disasters, is sending 21 people to Thailand, Indonesia and Sri Lanka. They will determine the extent of the damages and what contributions the United States should make.

The United States Pacific Command (search) has also dispatched P-3 patrol aircraft stationed in Kadena air base in Okinawa, Japan, to Utaphao, Thailand, to conduct survey operations, including a possible role in search-and-rescue efforts. The Navy has not reported any damage to its ships or bases in the region.

Powell said eight Americans are confirmed dead, five in Sri Lanka and three in Thailand. Hundreds of Americans were injured and others are still missing. Powell said U.S. embassy officials are trying to locate those missing U.S. citizens.

The secretary said the State Department has set up a hotline for family members seeking information about relatives in the tsunami-struck areas. The number 1-888-407-4747 provides a recording, but gives some other contact information. Other information about general relief and emergency services is also available on the State Department's Web site at http://travel.state.gov/travel/crisismg.html.

Carol Miller of the International Red Cross told FOX News that first aid, field assessment and coordination teams are already on the way to the affected countries to find out what the needs are on the ground, but individuals who want to contribute financial assistance are also welcome to call 1-800-HELP-NOW or go online to http://www.redcross.org.

The tsunamis (search) that stretched across the Indian Ocean were triggered by a 9.0-magnitude earthquake Sunday morning that hit off the western coast of Indonesia's Sumatra island. While reports differ, Sri Lanka, 1,000 miles from the quake's epicenter, suffered the highest number of casualties, with more than 12,000 reported dead. Indonesia (search) had 5,000 dead, India 3,000 and Thailand (search) listed 339 dead, including the grandson of that nation's King Umepon. The Maldives, Myanmar, Bangladesh and Somalia together reported hundreds of casualties. Twenty-two nations not directly hit by the tsunamis reported citizens missing or dead.

Powell said while aid is on its way, the impact of the devastation will be felt for a long time to come.

"Some 20-plus thousand lives have been lost in a few moments, but the lingering effects will be there for years. The damage that was caused, the rebuilding of schools and other facilities will take time. So you need a quick infusion to stabilize the situation, take care of those who have been injured, get immediate relief supplies in, and then you begin planning for the longer haul," he said.

Powell said he spoke with President Bush on Monday morning and the president is closely monitoring the situation from his ranch in Crawford, Texas. Powell said the administration has expressed its deepest condolences to the families of those affected by the tragedy.

At Crawford, known as the western White House, Deputy Press Secretary Trent Duffy said the United States "will be a leading partner in one of the most significant relief, rescue and recovery challenges that the world has ever known."

Duffy said U.S. embassies have been working since Sunday morning to help Americans in the region. Bush has written letters to the leaders of seven countries hardest hit by tsunamis.

"Again, this is a terrible tragedy. There is a significant loss of life. And our thoughts and prayers are with all those who are suffering," Duffy said.

FOX News' Mike Emanuel, Teri Schultz and Sharon Kehnemui Liss contributed to this report.