Three girders of the 1.4-km-long flyover collapsed around 7.30 p.m. Saturday, Xinhua reported.
Rescuers pulled out six bodies from under the debris, while hospital officials said three more died during treatment.
Protesting the delay in the rescue operations, hundreds of people demonstrated and set ablaze construction materials after the incident.
Police fired tear-gas shells as protesters vandalised several vehicles. At least 10 motorcycles were also set on fire.
The Bangladesh army was called in to assist the Rapid Action Battalion, Border Guard Bangladesh and police in the rescue operation.
Dhaka: At least nine people were killed and many injured when an under-construction flyover collapsed in Bangladesh's southeastern port city of Chittagong, police said Sunday.
First Published: Sunday, November 25, 2012, 13:45