Brasilia: Gunmen opened fire in a disco in the southern Brazilian city of Porto Alegre early Tuesday, killing one man and injuring another 16 persons, police and hospital sources said.
A 19-year-old man died of his injuries following surgery, a hospital spokesman told AFP.
The spokesman said six people remained hospitalized by late afternoon.
Witnesses said the shooting erupted after a woman walked into the packed venue and handed out guns, police major Jose Carlos Pacheco told AFP.
He added four people had been arrested.
Police suspect the incident, which occurred around 3:30 am (0530 GMT), involved either an attempted score settling by rival gangs or a revenge attack by a clubber injured several weeks ago in a clash with a disco security guard.
"Many questions must be answered," said Pacheco.
"How did a woman manage to walk in with a sackful of fire arms without either the metal detector or the security on the gate being aware of it? And why, today of all days, were the security cameras not working?"
He added the disco had a history of violent incidents, including previous shootings.