HOUSTON, Texas (KTRK) -- Authorities have charged a second man in the shooting death of a Lamar High School student.Authorities arrested and charged 18-year-old Dave'on Thomas with murder.He's the second person charged in the shooting death of Delindsey Dwayne Mack.On Nov. 13, Mack was shot multiple times as he walked on Bammel Lane during Lamar's first lunch period.Police say the shootings were gang-related and a part of back-and-forth shootings between the 103 and YSB gang.Kendrick Johnson was arrested in March and charged with the murder in connection with Mack's death as well.