The suspect, Sergei Pomazun, 32, allegedly started shooting people at random Monday from a hunting shop in Belgorod.
He then fled from the scene in a vehicle with two hunting rifles from the store, RIA Novosti said.
Five victims died at the scene, police said while a sixth died later at a hospital. A 14-year-old girl was among the dead.
RIA Novosti said police found Pomazun's car after the shooting, but the suspect remains at large.
Pomazun has a criminal record and once served four years for theft, RIA Novosti said.
Earlier reports suggested a second suspect was involved in the shooting but police said Tuesday Pomazun acted alone.