A cargo plane crashed in flames into a residential area in Pakistan's largest city soon after take-off, killing all eight Russian crew aboard but narrowly missing several densely-populated apartment blocks.

At least one person on the ground was injured when the Russian-made plane slammed into a housing complex under construction in Karachi yesterday, sending fire and smoke into the sky and razing or damaging about 20 buildings.

Authorities were searching the smoking rubble today for any additional survivors or bodies.

The crash was the second this month in Karachi, the main port city in the south, and the third in Pakistan in less than five months.

Residents said most of the houses destroyed were being built and believed unoccupied except for a few labourers. They said hundreds more could have died if the plane had hit one of several large apartment buildings only a few hundred yards away.

The Sudan-bound plane crashed at around 1.50am, when many people in the upmarket neighbourhood were asleep. One of the plane's engines was on fire as it flew overhead, several witnesses said.

"I saw one of its wings was burning and there was a blast and the fire engulfed the aircraft very quickly," said Riaz Ahmed.

Aviation authority spokesman Pervais George said the plane came down two minutes after take-off from the city's international airport. He said the eight crew, all Russians, were dead.

Many people initially thought the blast was from a bomb, a regular event in militant-torn Pakistan.

"I was sleeping and the huge blast awoke me. I thought some suicide attack might have occurred and I ran outside," said Rehan Hashmi.

Local doctor Abdul Razak said one person was being treated at a hospital for severe burns.

Fire engines sprayed foam on to the crash site and the blaze was extinguished after two hours.

Hundreds of people came to see the spectacle and film it with their mobile phones, hampering access for emergency workers.

Most of the housing complex was reserved for naval officers and their families.

Mr George said the plane was an Ilyushin Il-76, a multi-purpose cargo plane often used for ferrying humanitarian aid to developing countries, as well as other large items.

Earlier this month in Karachi, a small passenger plane crashed soon after take-off, killing 21 people.

In July, a passenger jet operated by Pakistani carrier Airblue crashed into hills overlooking the capital Islamabad during stormy weather, killing all 152 on board.