BATON ROUGE - Police arrested a 15-year-old allegedly involved in a fatal triple shooting. 

An 18-year-old, Lenni Douglas, was shot and killed shortly before 10:30 p.m. May 31 near Prescott Court. Police said Douglas was trying to break up a fight between a woman's new boyfriend and her ex when the shooting happened. Douglas died at the scene, and two others were injured. 

Thursday, the Baton Rouge Police Department arrested a 15-year-old in connection with the shooting. The teenager was booked into the Juvenile Detention Center for first-degree murder, two counts of attempted first-degree murder, illegal use of a weapon, and criminal damage to property.