Dhaka  - At least four persons were killed and 20 injured in a devastating fire Friday at Basundhara City, Bangladesh's largest shopping mall, in Dhaka, officials said.

Firefighters recovered three more charred bodies from inside the debris on the upper floors of the 21-storey building, in which the top five floors were destroyed, Tejgaon zone police chief Mahbubur Rahman said.

Earlier, a firefighter of the Basundhara group was killed and 20 people sustained burn injuries.

The fire broke out at around 1400 (0800 GMT) and quickly engulfed the Basundhara group's corporate office, housed on the upper floors, turning the building into a towering inferno in the heart of Dhaka.

The blaze was finally brought under control after five hours of joint effort by rescue workers from the army, navy, air force and fire service and civil defence authorities.

Fire Service and Civil Defence Department head Abu Nayeem Mohammed Shahidullah told reporters that four storeys, the 15th to 19th, were incinerated, while two more floors were partially burned. The blaze had started on the 17th floor.

Firefighting units late Friday were extinguishing remnants of the flames, and seeking any people still trapped inside the building, said Mahbub Morahed, Basundhara group Vice President.

"We cannot figure out the actual loss of assets as the rescue operation is ongoing. But almost all the corporate offices of the group have been gutted," he said.

Firefighters said at first they could only watch the fire spread as they lacked equipment to reach the 14th floor.

As the fire broke out, hundreds of shoppers poured out of the main entrance of the building to join the crowds of spectators that had gathered on nearby streets.

No shops however were damaged, said Zahidur Rahman, a security officer at the Basundhara City complex which opened to the public in August 2004.

The building's bottom eight floors contain nearly 2,500 retail shops, a food court, a cinema, and a sports zone, he said.

Basundhara group used the upper floors of the 100 million-dollar building as its corporate headquarters, running businesses including real estate, construction materials, household products and paper.

The Bangladesh government ordered an investigation into the accident and assigned a three-member committee headed by a senior Home Ministry official to probe the fire, Home Secretary Abdus Sobhan said. An official probe was to begin Saturday. (dpa)