At least 16 people were killed and dozens of others were injured after a blast rocked an office building in the commercial district of Bangladesh's capital Dhaka on Tuesday.

The cause of the blast remained unclear but fatal building fires and explosions are common in Bangladesh, where safety enforcement is often lax.

The blast shook the fourth and fifth floors of a seven-story building in Gulistan, a major hub for wholesale goods in Dhaka. Several floors of the building and the side walls were destroyed in the explosion, which sent rubble and splinters flying into crowded streets.

More than 100 people were treated for head wounds, fractures and other injuries at the Dhaka Medical College Hospital, hospital director Nazmul Islam told AFP. "At least 15 people have died, including two women," he said, adding that hundreds of doctors and nurses had been mobilised to treat the injured.

No substantial fire broke out in the building, which housed dozens of warehouses, shops selling bathroom fittings, and other commercial spaces. More than 150 firefighters were at the site to assist in rescue efforts, a fire services spokesperson said.

"Our officers are investigating whether it was an act of sabotage or an accident," police commissioner Khandaker Golam Faruq told reporters.

A bus driver caught in the blast said 30 of his passengers were injured when his vehicle passed the building as the blast hit. "I heard a loud explosion and then I was hit in the head by a flying object," he told reporters. Another witness said people were trapped on the second, fourth and fifth floors of the building when firefighters arrived and rushed them to the hospital.

Explosions and fires due to gas cylinders, faulty air conditioners and bad electrical wiring are frequent in Bangladeshi buildings and factories. They occur mostly between November and March when the weather is dry and cold.

An explosion at an oxygen plant near the southern port city of Chittagong on Saturday killed seven people. A fire and subsequent explosions at a container depot in the same city in June last year killed more than 50 people.