CCTV footage shows a dentist and a patient fleeing as the deadly earthquake struck a clinic in Myanmar.

The woman was in the dentist's chair undergoing a tooth extraction when the tremors rattled the Chan Nyein Dental Clinic mid-way through the surgery in Mandalay on March 28.

They all scrambled to safety outside as the quake rattled shelves and tables full of medical equipment.

The US Geological Survey said the magnitude 7.7 tremor struck at a depth of 10 kilometres (six miles), and was centred in Myanmar, around 50 kilometres (30 miles) east of Monywa, along the Sagaing fault.

Residents ran from their homes when they felt the tremors shortly after 1:20 pm local time on March 28. More than 3,145 people in the country have been killed and some 4,589 injured, with the figures expected to rise.

The quake destroyed buildings, bridges, and dams, leaving many areas in ruins. Communication remains difficult as mobile networks are down, and access to electricity and the internet is limited.

In neighbouring Thailand, high-rise buildings shook and an apartment block under construction collapsed in Bangkok. The Bangkok Metropolitan Administration said at least 22 people were killed.