Story highlights Tensions erupted after pickup trucks brandishing Confederate flags drove by a party

A grand jury indicts 15 people, alleging they made terroristic threats

Members of the Respect the Flag group have said rock-throwing started the altercation

(CNN) Months after a convoy of pickup trucks waving large Confederate flags rumbled past a birthday party in suburban Atlanta, a grand jury has indicted members of the group on terror-related charges.

The indictments charge 15 members of an organization known as Respect the Flag with violating Georgia's Street Gang Terrorism and Prevention Act and making terroristic threats. If convicted, they could face up to 20 years in prison.

Melissa Alford, who hosted the July birthday party, where many of the attendees were black, said tensions flared when the trucks drove by the home in Douglasville, Georgia. The people holding the flags were also brandishing weapons, she said.

"They used the N-word and said they were going to kill people on my property," Alford told CNN affiliate WSB

Members of Respect the Flag have described the day's events differently, telling the Atlanta Journal-Constitution that someone at the party threw rocks at them, triggering the altercation.

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