Prosecutors say four alleged members of Chicago's Black P Stone Nation street gang have been indicted on federal drug charges for allegedly selling crack cocaine on the city's South Side.

The four indictments issued separately Thursday are the result of an undercover investigation conducted by Chicago police and federal agents.

The four have been identified as 31-year-old Randy Smith, his 26-year-old brother, Herman Smith, 33-year-old Michael Smith and 25-year-old Timothy Moses.

The charges against Randy and Herman Smith and Moses carry a mandatory minimum of 10 years in prison and a maximum of life imprisonment without parole and a maximum fine of $4 million. Michael Smith faces a mandatory minimum of 5 years in prison and a maximum of 40 years and a $2 million fine.