HANOI (AFP) - At least seven people were killed in Hanoi on Friday (April 12) after a deadly fire engulfed several manufacturing workshops and warehouses, state media reported.

The overnight fire engulfed small plants making recycling bins and silica gel sachets as well as storage centres for frozen goods and wooden products, according to the official Vietnam News Agency.

VNA earlier put the toll at five, later revising it up.

"The authorities took out two more bodies of five victims of the fire at the workshops... bringing the number of dead to seven," it reported after the fire in Hanoi's residential Nam Tu Liem district.

One remained unaccounted for by late Friday afternoon.

The fire started in the early hours of the morning and was extinguished by dawn. Police said they were investigating the cause.

Images from the scene showed firefighters removing bodies from the charred site, with sheet metal roofing collapsed among the burnt debris.

Witnesses said the blaze quickly swallowed the workshops and warehouses, informal commercial buildings commonly seen across Hanoi.

"In just 20 minutes, the fire from the plastic workshop went up really high... no one was able to approach it because the fire was too strong," witness Vu Van Can told state-run news site VnExpress.

Big blazes are relatively common in Vietnam, where fire prevention and firefighting services remain underdeveloped.

Thirteen people were killed in an apartment complex fire in Ho Chi Minh City last year after the high-rise was engulfed in flames overnight, trapping many inside their homes.

That was Vietnam's deadliest fire since 2016, when a blaze in a karaoke bar in Hanoi left 13 people dead, Most were government workers who died in the club's soundproof chambers.