Fans were jumping up and down in celebration towards the end of a match when a section of concrete gave way in the upper terraces, say police. The hole was reported to be several metres wide and victims fell some 40m to the street below.
About 60,000 fans turned out to watch the game in the 66,000 capacity stadium, but most people only became aware of the collapse after the final whistle had blown.
The 56 year old Fonte Nova stadium was evaluated as part of a study of Brazilian soccer venues last month, following FIFA's announcement that Brazil is to host the 2014 world cup. The survey released last month by Brazil's Sinaeco association of architects and engineers said the Fonte Nova's stands were "in ruins," according to reports.
The governor of Bahia state, Jacques Wagner, ordered the closure of the stadium while the authorities investigate the causes of the accident.