A serviceman opened fire on fellow soldiers and civilians near Sevastopol, the region's governor, Mikhail Razvozhayev said, Vedomosti reports.
The incident occurred in the village of Khmelnitskoye, leaving four people dead and four others injured.
According to the governor, the serviceman first opened fire on his fellow soldiers, killing one and wounding another.
He then went to the village, where he shot dead two men, aged 71 and 59, and a 64-year-old woman.
Three more civilians were injured.
The suspect has been detained, and the wounded are receiving medical treatment.