MANDALAY, Myanmar >> The smell of decaying bodies permeated the streets of Myanmar’s second-largest city 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 106-degree heat, with only the occasional 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 continuing aftershocks might cause structures left unstable to collapse.

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.

“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 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 were 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.

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 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.

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. 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.

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.

An initial report on earthquake relief efforts noted the severe damage or destruction of many health facilities, and warned that a “severe shortage of medical supplies is hampering response efforts.”