Forty-nine alleged gang members have been arrested in Gwinnett County in connection with violent crimes surrounding an apartment complex, among them drug dealing, robberies of high school students and a murder.

On Monday, investigators from the Gwinnett County Police Department and agents from the Bureau of Alcohol, Tobacco, Firearms and Explosives said the mass arrests stemmed from an eight-month investigation of two loosely affiliated street gangs.

One group called itself “Ninth Ward” in deference to a New Orleans neighborhood of the same name. Several of its members moved to the metro Atlanta area from the Louisiana city following Hurricane Katrina, said Scott Sweetow, an Atlanta-based ATF agent.

Detectives declined to name the second gang, indicating they expected more arrests.

Members of both gangs at various times claimed to be affiliated to the larger “Gangster Disciples” organization, which federal officials said originated in Chicago. The Gangster Disciples often are identified by symbols such as a black bandana, six-pointed star and pitchfork, Gwinnett police gang unit Detective James Evans said.

Much of the gang activity was concentrated in the Bradford Gwinnett apartment complex in unincorporated Norcross. An investigation began in February following an anonymous email sent by someone in the apartment complex, said Gwinnett County Police Chief Charles Walters.

Police said they observed and documented numerous instances in which the two gangs worked allegedly together in committing burglaries and drug sales. Detectives used social media to track respective gang activities because the members “like to brag about what they do,” Sweetow said.

Violent episodes followed. On April 6, Daryl Fuller, 20, was shot and killed by gang unit investigators. Fuller allegedly drew a firearm on the officers as they approached him and two other men near the intersection of Singleton Road and Sarah Court in unincorporated Norcross.

Brandon Mosely and Hunter Davis have been charged with murder and aggravated assault for allegedly shooting a man at The Columns at Paxton Lane apartments in unincorporated Lilburn on June 28, law enforcement officials said.

The eight-month investigation led to a Dec. 14 warrant sweep in which authorities arrested 31 individuals. Suspects were charged in connection with 16 burglaries and might be responsible in up to 50 more, said Gwinnett County Police Chief Charles Walters.

Seventeen of the gang members were jailed on drug-related charges.

Evans said gang members monitored the activities of apartment complex visitors by stationing lookouts at the only entrance to the complex.

“It was common knowledge that if police [were called], they would tell [the residents], ‘If you ever do that again we’re going to rob your house, we’re going to shoot you,’” Evans said. “They just kept the community in fear.”

At the complex on Monday afternoon, Staci English rounded up her five children who ranged in age from one year to 11. English said she kept her kids inside to avoid trouble in the complex, though she wasn’t aware of the extent of what was going on until the arrests occurred.

“That concerns me,” English said, frowning. “I don’t have the funds to move; this is what I can afford, so we just stay in the house.”