A fire has broken out at a major mall complex in Thailand's capital, with initial reports from Thai emergency services saying one person has died and two were injured.

The cause and extent of Wednesday's fire at Bangkok's Central World complex, which includes a hotel and an office tower, was not immediately known.

The report of casualties came from the city's Erawan Emergency Radio network.

Images posted by social media users showed thick black smoke pouring from the complex, with hundreds of evacuated shoppers filling a large open square next to the mall.

The fire broke out during the congested city's evening rush hour. Sirens from emergency vehicles wailed as they tried to make their way through gridlocked traffic.

Central World sits at a major intersection surrounded by shopping complexes, shrines and high-rise hotels popular with foreign tourists. It is near the main junction for Bangkok's elevated train lines, as well as the Erawan Shrine, which was the site of a deadly bombing in 2015.

The mall typically would have been busy with shoppers as well as diners headed to the many restaurants inside.

The Central World complex was among several Bangkok buildings set on fire by arsonists during mass anti-government protests in 2010.