( CNN ) -- A massive emergency response operation is under way in northern Japan , with world governments and international aid groups coming together to bring relief to the beleaguered island nation . According to Japan 's Foreign Affairs Ministry , 91 countries and regions and 6 international organizations have extended offers of assistance . The Japanese government has received 11 urban search and rescue teams , the group said in a situation report , including teams from the United States , South Korea , Australia , Germany , Mexico , New Zealand , China , Hungary , Singapore and the United Kingdom . Japan 's own search and rescue team was in New Zealand , assisting with recovery from the recent Christchurch earthquake , when the quake and tsunami struck Japan on Friday . Here is a sampling of relief efforts under way : . . United States . . Ten U.S. helicopters flew missions Monday finding people in need of help and delivering water , food and blankets , Pentagon spokesman Col. David Lapan said . Additional helicopters conducted surveys of at-sea debris as well as search-and-rescue operations along the coast , Lapan said . Eight U.S. Navy ships are now at work off the Japanese coast , with five more on the way in coming days and weeks , Lapan said . Some military personnel on the USS Ronald Reagan off the East Coast of Honchu set off alarms indicating radiation and were decontaminated with soap and water , according to Lapan . The ship was about 100 miles from the damaged Japanese nuclear reactors at the time and subsequently changed its position , he said . Lapan said those who registered `` very low levels '' of radiation included flight crews on helicopters returning to the ship , as well as crew members who never left the ship . He was unable to say how many people had to be scrubbed down but added that they were n't wearing protective gear and that none had been given radiation-blocking potassium iodide in response . Two search-and-rescue teams from the United States arrived in the hard-hit coastal city of Ofunato , which was severely damaged in the quake . It took their convoy six hours to travel from Misawa Air Base on Monday . Nearly 150 people and 12 dogs trained to detect live victims arrived in Japan late Sunday , according to Los Angeles Fire Department Inspector Don Kunitomi . Hailing from California and Fairfax County , Virginia , the teams are the only two in the United States qualified to respond to disasters on such a scale , Kunitomi said . `` There are a lot hazards that have never been experienced by a search-and-rescue team , '' Kunitomi said . `` There 's this radiation factor . We do have radiation equipment ... but no one has ever really experienced this . '' `` It looks like it 'll be part Katrina because of the flooding and part New Zealand because of the earthquake , '' he continued , referring to Hurricane Katrina in 2005 and last month 's earthquake in Christchurch , New Zealand . The teams traveled in a convoy of two buses , several flatbed trailers and half a dozen utility vehicles . The U.S. Agency for International Development ( USAID ) is coordinating the overall American response . The United States is also sending experts from the Department of Energy and the Nuclear Regulatory Commission to offer technical assistance to the Japanese government . On Sunday , the USS Ronald Reagan started delivering aid in the coastal regions of Japan 's Miyagi Prefecture . Crew members , in conjunction with the Japan Maritime Self Defense Forces , conducted 20 sorties delivering aid pallets . Eight U.S. and Japanese helicopters were used to distribute the pallets , according to Sgt . Maj. Stephen Valley of U.S . Forces Japan . . China . . A 15-member Chinese search and rescue team has begun work in Ofunato , according to China 's state-run Xinhua news agency . The group brought 4 tons of material and equipment and is expected to work in the area for up to 10 days , the agency reported . The gesture comes just six months after the two countries sparred in a territorial dispute over the Diaoyu Islands in the East China Sea . Tokyo held a Chinese trawler captain after his fishing boat collided with Japanese coast guard ships near the islands in September . There also remains a great deal of tension between China and Japan , left over from Japan 's invasion and occupation of part of China from 1931 to 1945 . The wartime atrocities still fuel widespread distrust of Japan by many Chinese . However , `` China is also a country prone to earthquake disasters , and we fully empathize with how they feel now , '' Chinese Premier Wen Jiabao said Monday . China has been hit with two devastating quakes in the past three years . And it is conducting domestic quake rescue efforts in southwestern Yunnan province after a deadly 5.8-magnitude quake Thursday . . United Kingdom . . A British team comprising 63 fire service search-and-rescue specialists , two dogs and a medical support team is in Japan , the U.K. foreign office said . The group has 11 metric tons of rescue equipment , including heavy lifting and cutting equipment to extract people trapped in debris , the government said . . New Zealand . . New Zealand has sent a rescue team of 10 from Christchurch to the hard-hit Japanese coastal city of Sendai . Christchurch is cleaning up from its own earthquake on February 21 that killed 123 people . . Mexico . . A Mexican rescue squad made up of eight search and rescue specialists , five dogs , two structure assessment specialists , members of the Mexican Red Cross and personnel from the National Autonomous University of Mexico is in Sendai , the Mexican Foreign Affairs Ministry said Monday . . International Groups . . The International Atomic Energy Agency 's Incident and Emergency Centre has offered technical assistance to Japan in the wake of an explosion at the Fukushima Daiichi plant . The government has evacuated more than 200,000 residents from homes close to the plant and tested 160 people for radiation exposure , authorities said Sunday . In addition to the response from world governments , humanitarian assistance groups have sent teams to hard-hit areas across Japan . The International Federation of Red Cross and Red Crescent Societies has 62 teams in-country providing assistance , according to a United Nations situation report . A Red Cross hospital in the city of Ishinomaki , which was engulfed by the tsunami , is the primary medical facility providing health care services in the area , according to the International Red Cross ' Patrick Fuller . He says the focus is very much on search and rescue at the moment , adding that the group is particularly concerned about Japan 's large population of elderly people who are vulnerable to hypothermia . The World Health Organization has alerted its network of health experts who specialize in nuclear-related disasters . The Radiation Emergency Medical Preparedness and Assistance Network is now on standby , ready to assist if requested by Japanese authorities . The network is made of representatives from more than 40 institutions with expertise in radiation emergency medicine , public heath interventions and long-term followup . Mercy Corps International teamed with Peace Winds Japan to rush aid to affected regions . On Sunday , Peace Winds conducted assessments in two northeastern cities , Ishimaki and Kesennuma , according to a statement on Mercy Corps ' website . On Monday , the group will use helicopters to bring in 30 family-sized tents , plus materials to construct a 100-person balloon shelter . Peace Winds has expert responders on their way to remote areas of northern Japan , where they plan to distribute large emergency tents , water , food and blankets , according to Mercy Corps ' website . The two groups are working to deliver other essential items that are in short supply . Medecins sans Frontieres has a 10-member team working in Miyagi Prefecture , assisting `` in the massive government-led relief effort . '' `` On Sunday , we conducted mobile clinics and assessments in two evacuation centers , '' team coordinator Mikiko Dotsu said in a news release . `` It appears that medical needs are increasing in evacuation centers . '' Additional personnel will join the group Monday , which will then split in two to cover more ground . The teams will begin working their way into more remote areas , focusing particularly on the needs of vulnerable populations like elderly people and young children . Stephen McDonald of Save the Children said Sunday that his group had multiple teams in the country , reaching out to families left homeless . There are water shortages at evacuation centers , creating hygiene challenges , he said . . Celebrities . . Celebrities from Lady Gaga to Linkin Park rallied their fans to ante up for earthquake and tsunami relief in Japan . Lady Gaga is offering a red-and-white wristband with the words `` We pray for Japan '' and an image of the singer 's monster paw gesture . Mike Shinoda of Linkin Park has designed a T-shirt to benefit Music for Relief 's Tsunami Relief in Japan . The Red Cross appeared to be the charity of choice among celebs , who encouraged their fan bases to make donations via text message . CNN 's Nick Valencia , Kim Hutcherson , Brian Walker , Michael Martinez and Sarita Harilela contributed to this report .
NEW : Mexican rescue squad arrives in Sendai . U.S. search and rescue teams are in hard-hit Ofunato . Japan says it will send a ship to help with the relief effort. China sends team despite long-running tensions with Japan .