LONDON — There is still time to save lives — that’s why governments and aid agencies Sunday rushed doctors, volunteers and equipment to Nepal without waiting for the dust to settle.

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.”

Diarrhea was already a growing problem and a measles outbreak was feared, with vaccines in short supply, the U.N. warned in a report.

Substantial logistical hurdles remain, but there were hopeful signs as Kathmandu’s international airport reopened after Saturday’s crushing earthquake, though there were still delays as aftershocks continued. Some aid vehicles were able to travel overland from Indian to the stricken Nepalese city of Pokhara.

“That means supplies could potentially come in overland from India. That is a positive sign,” said Ben Pickering, Save the Children’s humanitarian adviser in Britain. “The airport opening is a small miracle.”

He cautioned that chaotic conditions may create a bottleneck at the airport as governments and aid agencies try to bring in personnel and supplies in the coming days.

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: cash.me/$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.

Other charities face similar roadblocks.

International Search and Rescue Germany said a team of 52 relief workers including doctors, experts trained in searching for people buried under rubble and several dog squads are flying Sunday. The team will bring a mobile medical treatment center.

Spokesman Stefan Heine said the priority was to get to the scene of the quake as quickly as possible to find those still alive.

They will be supported by numerous governments that have announced plans to send aid worth millions of dollars.

The Pentagon said a U.S. military plane departed Sunday morning for Nepal carrying 70 personnel, including a U.S. Agency for International Development disaster assistance response team, an urban search and rescue team from Fairfax, Virginia, and 45 tons of cargo.

The United Arab Emirates deployed an 88-member search-and-rescue team to Nepal Sunday, and the Emirates Red Crescent also sent a team.

The Israeli military said it is sending a 260-member mission to Nepal to provide immediate search-and-rescue help and medical aid.

“An advanced multi-department medical facility, equipped with approximately 95 tons of humanitarian and medical supplies from Israel and a medical staff of 122 doctors, nurses and paramedics, will be rapidly established in the city of Katmandu to provide medical care for disaster casualties,” the Israeli military said.

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.

Canada sent an advance unit from its urban disaster search and rescue team, along with medical personnel and humanitarian relief supplies.

Volunteers from various British charities gathered at London’s Heathrow Airport getting ready for overnight flights to the Nepal region.

Gary Francis, leader of the Search and Rescue Assistance in Disasters group, said the organization was bringing in enough tents, food and water to operate self-sufficiently for 15 days.

They were bring in “a vast array” of equipment including sound and vibration detectors, seismic listening devices, and cutting equipment, with an eye toward finding survivors.

“Once we are there we’ve got the ability to carry out a coordination role or urban search and rescue looking for survivors trapped in collapsed buildings,” he said.

U.N. humanitarian chief Valerie Amos said in a statement Sunday evening that the full picture of destruction and suffering would only appear worse “as humanitarian workers reach the more remote areas near the epicenter of the earthquake.” She said “entire areas have been flattened” and that time is of the essence in search and rescue efforts.