The smell of decaying bodies permeated the streets of Myanmar's second-largest city on Sunday as people worked frantically by hand to clear rubble in the hope of finding someone still alive, two days after a massive earthquake struck that killed more than 1,600 people and left countless others buried.

The 7.7 magnitude quake hit midday Friday with an epicenter near Mandalay, bringing down scores of buildings and damaging other infrastructure like the city’s airport.

Relief efforts have been hampered by buckled roads, downed bridges, spotty communications and the challenges of operating in a country in the midst of a civil war.

The search for survivors has been primarily conducted by the local residents without the aid of heavy equipment, moving rubble by hand and with shovels in 41-degree Celsius (106 Fahrenheit) heat, with only the occasional tracked excavator to be seen.

A 5.1 magnitude aftershock Sunday afternoon prompted screams from those in the streets, and then the work continued.

Many of Mandalay's 1.5 million people spent the night sleeping on the streets, either left homeless by the quake, which also shook neighboring Thailand and killed at least 18 people there, or worried that the continuing aftershocks might cause structures left unstable to collapse.

Many areas still have not been reached

So far 1,644 people have been reported killed in Myanmar and 3,408 injured, but many areas have not yet been reached, and many rescue efforts so far have been undertaken by people working by hand to try and clear rubble, said Cara Bragg, the Yangon-based manager of Catholic Relief Services in Myanmar.

“It's mainly been local volunteers, local people who are just trying to find their loved ones,” Bragg said after bring briefed by her colleague in Mandalay.

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“I've also seen reports that now some countries are sending search and rescue teams up to Mandalay to support the efforts, but hospitals are really struggling to cope with the influx of injured people, there's a shortage of medical supplies, and people are struggling to find food and clean water,” Bragg added.

The organization was sending a team by road on Sunday to assess peoples' most pressing needs so that it could target its own response.

With the Mandalay airport damaged and the control tower toppled in the capital Naypitaw's airport, all commercial flights into the cities have been shut down.

Official relief efforts in Naypitaw were prioritizing government offices and staff housing, leaving locals and aid groups to dig through the rubble by hand in residential areas, the hot sun beating down and the smell of death in the air.

A team sent from neighboring China rescued an older man who had been trapped for nearly 40 hours beneath the rubble of a Naypitaw hospital, and many others are believed to still be buried under, the official Xinhua news agency reported.

Myanmar sits on the Sagaing Fault, a major north-south fault that separates the India plate and the Sunda plate.

The earthquake occurred when a 200-kilometer (125-mile) section of the fault ruptured, causing widespread damage along a wide swath of territory down the middle of the country, including Sagaing, Mandalay, Magway and Bago regions and Shan State.

With widespread telecommunication outages, few details have come out so far from areas other than the main urban areas of Mandalay and Naypitaw.

Foreign aid starts to arrive in Myanmar

Still, two Indian C-17 military transport aircraft were able to land late Saturday at Naypitaw with a field hospital unit and some 120 personnel who were then to travel north to Mandalay to establish a 60-bed emergency treatment center, according to the country's Foreign Ministry. Other Indian supplies were flown into Yangon, Myanmar's biggest city, which has been the hub of other foreign relief efforts.

On Sunday, a convoy of 17 Chinese cargo trucks carrying critical shelter and medical supplies was expected to reach Mandalay, after making the arduous journey by road from Yangon.

The 650-kilometer (400-mile) journey has been taking 14 hours or longer, with clogged roads and traffic diverted from the main highway to skirt damage from the earthquake.

At the same time, the window of opportunity to find anyone alive is rapidly closing. Most rescues occur within the first 24 hours after a disaster, and then survival chances drop as each day passes.

An initial report on earthquake relief efforts issued Saturday by the U.N. Office for the Coordination of Humanitarian Affairs noted the severe damage or destruction of many health facilities, and warned that a “severe shortage of medical supplies is hampering response efforts, including trauma kits, blood bags, anesthetics, assistive devices, essential medicines, and tents for health workers.”

China said it has sent more than 135 rescue personnel and experts along with supplies like medical kits and generators and pledged around $13.8 million in emergency aid. Russia’s Emergencies Ministry said it had flown in 120 rescuers and supplies to Yangon, and the country’s Health Ministry said Moscow had sent a medical team to Myanmar.

Bangladesh rescue team to fly to earthquake-hit Myanmar Sunday: ISPR

Teams from Singapore have been working already in Naypitaw. Malaysia dispatched a team of 50 personnel on Sunday with trucks, search and rescue equipment and medical supplies. Thailand said 55 of its soldiers arrived in Yangon on Sunday to help with search and rescue operations, while Britain announced a $13 million aid package to help its locally-funded partners already in Myanmar respond to the crisis.

18 people reported dead in Thailand

In neighboring Thailand, the quake rocked much of the country, bringing down a high-rise building under construction in Bangkok, some 1,300 kilometers (800 miles) away from the epicenter.

So far, 11 people have been found dead at the construction site near the popular Chatuchak market. A total of 18 people have been reported killed by the quake in Thailand so far.

Rescue efforts in Myanmar complicated by civil war

In Myanmar, which is also known as Burma, rescue efforts so far are focused on Mandalay and Naypyitaw, which are thought to have been the hardest hit, but many other areas were also impacted and little is known so far about the damage there.

“We're hearing reports of hundreds of people trapped in different areas,” said Bragg. “Right now we're at 1,600 (known fatalities) and we don't have a lot of data coming out but you've got to assume it will be increasing in the thousands based on what the impacts are. This is just anecdotal information at this point.”

Beyond the earthquake damage, rescue efforts are complicated by the bloody civil war roiling much of the country, including in quake-affected areas. In 2021, the military seized power from the elected government of Aung San Suu Kyi, sparking what has since turned into significant armed resistance.

Government forces have lost control of much of Myanmar, and many places are dangerous or impossible for aid groups to reach. More than 3 million people have been displaced by the fighting and nearly 20 million are in need, according to the United Nations.

The government military has been fighting long-established militias and newly formed pro-democracy People's Defense Forces, and has heavily restricted much-needed aid efforts to the large population already displaced by war even before the earthquake.

Military attacks continued with airstrikes on Friday and reports of mortar and drone attacks on Saturday.

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Tom Andrews, a monitor on rights in Myanmar commissioned by the U.N.-backed Human Rights Council, called for the military to immediately call a ceasefire.

“Aid workers should not have to fear arrest and there should be no obstructions to aid getting to where it is most needed,” he said on X. “Every minute counts.”