It appears the official number of fatalities is 6. From tbo.com:

The Highway Patrol said Raven Griswell, 15, of Finger, and Sean Michael Driskill, 22, of Adamsville, died at the scene. Four others - Brook L. Pope, 20, of Selmer; Scarlett Replogle, 15, of Selmer; Kimberly A. Barfield, 17, of Adamsville; and Nicole Griswell, 19, of Selmer, died in hospitals.

All 6 victims were between 15 and 22.