Governments and charities from the United States to the Middle East rushed personnel and aid to Nepal Sunday after Saturday’s magnitude 7.8 earthquake and ensuing aftershocks rattled the Himalayan nation, leaving more than 2,700 dead and thousands injured according to Nepalese authorities.

U.N. spokeswoman Orla Fagan, who is heading to Nepal, said preventing the spread of disease is one of the most important tasks facing aid workers who are arriving.

"There are 14 international medical teams on the way and either 14 or 15 international search-and-rescue teams on the way," she said. "They need to get in as soon as possible. They will use military aircraft to get them into Nepal."

The Pentagon says a U.S. military plane has departed from the Dover Air Force Base in Delaware bound for the earthquake-stricken nation.

Onboard are 70 personnel, including a U.S. Agency for International Development disaster assistance response team, a Virginia-based search and rescue team and 45 tons of cargo to provide assistance to areas hit by Saturday's massive quake.

The Pentagon says the flight is expected to arrive at Kathmandu on Monday.

The first to respond, however, were Nepal's neighbors -- India, China and Pakistan, all of which have been jockeying for influence over the landlocked nation. Still, Nepal remains closest to India with which it shares deep political, cultural and religious ties.

Indian air force planes landed Sunday with 43 tons of relief material, including tents and food, and nearly 200 rescuers, India's External Affairs Ministry spokesman Vikas Swarup said. The planes were returning to New Delhi with Indian nationals stranded in Kathmandu. More aid flights were planned for Sunday.

India suffered its own losses from the quake, with at least 61 people killed there and dozens injured. Sunday's aftershock was also widely felt in the country, and local news reports said metro trains in New Delhi and Kolkata were briefly shut down when the shaking started.

A 62-member Chinese search and rescue team also arrived Sunday. 

European nations deployed as well: France said it would send 11 rescuers on Sunday; Britain announced that an advance team of eight had been sent and that a 5 million pound ($7.6 million) aid package would be available under a rapid response plan; Italy deployed a team of experts from its Civil Protection Department as well as it foreign crisis team; and the Swiss Foreign Ministry said a team of experts including a doctor, a building surveyor and water quality technician had left for Nepal on Sunday.

Poland is sending a rescue team to Nepal of 81 firefighters, together with heavy equipment and several dogs, as well several medics. The medics are expected in Nepal on Monday morning. The firefighters were delayed by aftershocks and confusion at Kathmandu's airport, said Pawel Fratczak, spokesman for firefighters. He said they are now due to arrive Monday afternoon.

Other countries sending support Sunday included the United Arab Emirates, Germany and France.

Pakistan prepared to send four C-130 aircraft, carrying a 30-bed temporary hospital comprising army doctors, surgeons and specialists. An urban search and rescue team was also sent with ground-penetrating radars, concrete cutters and sniffing dogs. Pakistan was also sending 2,000 ready-to-eat meal packs, water bottles, medicines, 200 tents, 600 blankets and other necessary items.

 The need is great: UNICEF said Sunday that nearly 1 million children in areas affected by the earthquake are in "urgent need" of humanitarian assistance. UNICEF staff reported dwindling water supplies, power shortages and communications breakdowns.

Celebrities like singer Shakira sent tweets appealing for help for UNICEF. The mobile payment company Square created a "cashtag" to donate:$unicef. PayPal announced it was waiving fees for donations to several aid organizations.

Information was still lacking about conditions at the earthquake's epicenter, Pickering said.

"Going forward it's about access to the epicenter, and helicopters are the key, but it's not clear whether they can be sourced and whether the high altitude is a problem," he said, adding that Save the Children has emergency kits pre-positioned in three warehouses in Nepal and plans to distribute bedding, buckets and other basic supplies to 2,000 families as quickly as possible.

Saturday's magnitude 7.8 earthquake spread horror from Kathmandu to small villages and to the slopes of Mount Everest, triggering an avalanche that buried part of the base camp packed with foreign climbers preparing to make their summit attempts. At least 18 people died there and 61 were injured.

The earthquake centered outside Kathmandu, the capital, was the worst to hit the South Asian nation in over 80 years. It destroyed swaths of the oldest neighborhoods of Kathmandu, and was strong enough to be felt all across parts of India, Bangladesh, China's region of Tibet and Pakistan.

By Sunday night, authorities said at least 2,430 people had died in Nepal alone, not including the 18 people that the Nepal Mountaineering Association says died in an earthquake-triggered avalanche on Mount Everest. Another 61 people died from the quake in India and a few in other neighboring countries. At least 721 of the deaths were in Kathmandu, and the number of injured nationwide was upward of 5,000. With search and rescue efforts far from over, it was unclear how much the death toll would rise.

The State Department confirmed Sunday that three U.S. citizens died in Nepal Saturday.

Dan Fredinburg, a Google executive who described himself as an adventurer, was among the dead.

Google confirmed his death. Lawrence You, the company's director of privacy, posted online that Fredinburg was in Nepal with three other Google employees climbing Mount Everest. The other three, he added, are safe.

According to the technology blog Re/Code, Fredinburg was an experienced climber who co-founded, in his spare time, Google Adventure. The project aims to "translate the Google Street View concept into extreme, exotic locations like the summit of Mount Everest or the Great Barrier Reef off Australia," according to Startup Grind, a global startup community.

Outside of the oldest neighborhoods, many in Kathmandu were surprised by how few modern structures collapsed in the quake. The city is largely a collection of small, poorly constructed brick apartment buildings.

With people fearing more quakes, tens of thousands of Nepalese spent Saturday night outside under chilly skies, or in cars and public buses. They were jolted awake by the aftershocks, including a powerful magnitude 6.7 aftershock in the Kathmandu region, on Sunday.

"The aftershocks keep coming ... so people don't know what to expect," said Sanjay Karki, Nepal country head for global aid agency Mercy Corps. "All the open spaces in Kathmandu are packed with people who are camping outdoors. When the aftershocks come you cannot imagine the fear. You can hear women and children crying."

Late Sunday, another magnitude 5.3 quake shook an area about 30 miles east of Kathmandu.

Nepal's worst recorded earthquake in 1934 measured 8.0 and all but destroyed the cities of Kathmandu, Bhaktapur and Patan.

In the Kalanki neighborhood of Kathmandu, police rescuers finally extricated a man lying under a dead person, both of them buried beneath a pile of concrete slabs and iron beams. Before his rescue, his family members stood nearby, crying and praying. Police said the man's legs and hips were totally crushed.

Hundreds of people in Kalanki gathered around the collapsed Lumbini Guest House, once a three-story budget hotel and restaurant frequented by Nepalese. They watched with fear and anticipation as a single backhoe dug into the rubble.

Police officer RP Dhamala, who was coordinating the rescue efforts, said they had already pulled out 12 people alive and six dead. He said rescuers were still searching for about 20 people believed to be trapped, but had heard no cries, taps or noises for a while.

The Kathmandu Valley is listed as a World Heritage site. The Buddhist stupas, public squares and Hindu temples are some of the most well-known sites in Kathmandu, and now some of the most deeply mourned.

The head of the U.N. cultural agency, Irina Bokova, said in a statement that UNESCO was ready to help Nepal rebuild from "extensive damage, including to historic monuments and buildings of the Kathmandu Valley."

Nepali journalist and author Shiwani Neupane tweeted: "The sadness is sinking in. We have lost our temples, our history, the places we grew up."

The Associated Press contributed to this report.