Yangon: At least 11 people were killed and dozens more injured in a large, unexplained explosion and fire in Myanmar's commercial hub and former capital Yangon early on Thursday, officials and witnesses said.

Residents in several areas of the city were woken by the blast around 2am local time (1930 GMT), which appeared to have occurred at a medical warehouse in the eastern township of Mingalar Taung Nyunt and sparked a large blaze, witnesses said.

A security official at the scene said seven men, including two firemen, and four women had died and 56 people were injured.

"We are still trying to make the list. We are also trying to find out the cause of explosion and the fire," the official said.

Another witness said some 50 to 60 injured people had been taken to hospital and fire rescue services were still working to put out the flames.

"We heard a very loud noise from the explosion and saw smoke in the sky. Our building was also shaken by the explosion. We have no idea what's happening," a resident in nearby Botahtaung township said.

Last week, a blast caused by an explosive device killed one woman and wounded another in northern Yangon.

While the cause of Thursday's incident remains unclear, Myanmar has been hit by several bomb blasts in recent years, most of them minor, which the authorities have blamed on armed exile groups or ethnic minority fighters.