The incident took place when about 15 gunmen arrived in three heavily armed cars at about 1:30 am (local time) on Saturday and started firing indiscriminately at the party-goers at Forro do Gago nightclub, police officials said.
According to local media, the gunfight went on for nearly half an hour as many people fled the club and took shelter in nearby houses.
At least eight men, four women, and two teenagers were reported to be shot dead. Also, six others, some of them children, were injured, according to the country's National Public Security Force.
The police believe that the shootings could be linked to a rivalry between drug gangs.
However, many of those killed are thought to have been innocent party-goers with no connections to any forms of organised crime. (ANI)