"Four men and three women were killed in the fire," the official told AFP, adding that goods worth some USD 5,000 had been destroyed in the blaze.
Local media reported that the victims were employees at the Gandamar wholesale department store building in Yangon's northeastern suburbs.
The fire started at 1:00 am (1830 GMT) and it was brought under control by firefighters after an hour. The fire department is still investigating the cause of the blaze, the official said.
Fires due to electrical faults are common in Myanmar due to low safety standards in the poverty-stricken country, which is emerging from decades of military rule.
This incident is the second deadliest fire in Myanmar this year after 13 teenage boys were killed at a Muslim school in April, the he added.
Substandard wiring was also blamed for the April fire at the Muslim school in Yangon. Dozens more students were rescued from that blaze.
Fire alarms and sprinklers are usually only installed at high-end hotels and some government buildings.
