The attack took place on Saturday morning in the poor area of Fortaleza, the EFE news agency reported.
A group of armed men drove up to the club and started shooting at the courtyard of the club. The agency notes that the cause of the incident could be proceedings due to drugs.
According to the television channel Globo, the victims were taken to hospitals, most of them are females.
The homicide division of the Fortaleza police told the AFP news agency that it was not yet possible to provide an official report, as the investigators were still there.
The site of the regional daily Diario do Nordeste quotes an anonymous police source who gives the figure of 18 dead, and evokes the settling of accounts between rival factions of drug traffickers.
The same source reported that the shooting took place at around 1:30 a.m. when a group of heavily armed men arrived in three vehicles and burst into Forro do Gago club in the district of Cajazeiras, in the center of Fortaleza.
In 2017, the state of Ceara, with a capital of Fortaleza, recorded a record of 5,114 homicides, 50% more than in 2016.
At the national level, Brazil recorded a surge of deadly violence in 2016, with 61,619 homicides, or seven per hour on average.