Acting county Prosecutor Robert Laurino says it's not clear what sparked the shootings of 19-year-old Francisco Sierra and 28-year-old Geraldo Criado.
No arrests have been made.
Detective Hubert Henderson, a city police spokesman, said the shootings happened around 3:40 a.m. at El Nuevo Gurabo, a small social club in the city's North Ward. Both men were shot in the upper torso and were taken to University Hospital in Newark, where they were pronounced dead a short time later.
Laurino said two other people - a 13-year-old and a 21-year-old - were wounded around 7:30 a.m. Saturday in an area not far from the club. They were also taken to University Hospital and authorities said they were expected to recover from their wounds.
But authorities don't believe the shootings are connected.
Club members and residents who live near the club said they were surprised that a violent incident happened at El Nuevo Gurabo, which has a largely Hispanic clientele. They described it as a small, quiet gathering place and said its owner is very involved in the community, noting that he sponsors several sports teams and activities for children.
Club member Hector Rodriguez told The Star-Ledger of Newark that El Nuevo Gurabo has a small paid membership, and they are allowed to bring guests. It was not clear Saturday afternoon if Sierra or Criado were members.
"We don't think the people involved in this were regulars," the Belleville resident told the newspaper. "Most of the people that come here are people we know."
Rodriguez described his fellow club members as nice people who usually go to the club to enjoy good music and talk into the night.