TEHRAN, Young Journalists Club (YJC) - Local media reported that 14 people had been killed in the shootings at a nightclub in the city of Fortaleza.
At least six others, some of them children, were injured, according to the country's National Public Security Force.
Police believe the shootings could be linked to a rivalry between drug gangs but many of those killed are thought to have been innocent party-goers with no connections to organised crime.
Up to 15 gunmen arrived in three heavily armed cars at 1.30am on Saturday and fired their weapons as they entered Forró do Gago nightclub.
People fled the club and sheltered in nearby houses as shots went on for half an hour, witnesses told O Globo,
Footage of the aftermath showed blood on the ground outside the club in the Cajazeiras area of Fortaleza, a coastal city in the state of Ceará.
The newspaper said the shooting was the deadliest in the city's history.
Twelve people died at the scene and two others were pronounced dead later in hospital.
At least men, four women, and two teenagers were reported to be among the dead.
A 12-year-old boy and two 16-year-old girls were said to be among the wounded survivors.
Police deployed a helicopter in the search for the gunmen but there are no reports of arrests. Witnesses were said to be scared of providing information to authorities out of fear of reprisals.
Ceará has the second highest levels of violence among Brazilian states, according to the newspaper Estadao, with drug traffickers blamed for increasing bloodshed.