By The Straits Times
Asia News Network
Local reports indicated an unspecified number of people were trapped under debris as videos of people screaming and rushing out of the building went viral online.
The balcony was located above the main lobby of the building and near where visitors are screened and checked before entering.
When it collapsed, hundreds of office workers were leaving for lunch.
But after the initial period of chaos, many rushed back in to help carry out the injured found amid bent steel structures, broken glass, and other debris of what was left of the balcony.
Reuters reported that the director of the stock exchange, Alpino Kianjaya, declined to comment on the incident. Markets are currently in midday break and will reopen at 1.30pm local time.
The cause of the collapse is not known, but initial reports do not point to a terrorist attack.
The IDX is located opposite Pacific Place, a popular mall in the Sudirman Central Business District.
It is also about 1km away from the recently renovated Gelora Bung Karno Stadium, which was officially opened by President Joko Widodo on Sunday.
The stadium is the key feature among other sporting facilities in the area which have been undergoing construction for the 2018 Asian Games, to be held in Jakarta and Palembang from Aug 18 to Sept 2 this year.