Police say gunmen barged into a party and shot dead "a large number of people" in northeastern Brazil.

A police officer at the homicide division in the city of Fortaleza said by telephone that the killings took place early Saturday morning near the Arena Castelao soccer stadium that was used in the 2014 World Cup of soccer.

He did not provide more details not confirm the number of dead and injured. Local press reports said 18 people were killed and six injured.

Repeated calls to the police press office went unanswered.

The police officer spoke on condition of anonymity because he was not authorized to speak to the press.