Irina Nomokonova, a senior aide to the Primorye Territory prosecutor, said police are searching for a group of young people who perpetrated the attack, on the night of December 10.
"The victims were hospitalized with various bodily injuries. One of them died in hospital the following day," she said.
Nomokonova said a special investigation group has been set up to probe the case.
Russia has seen a wave of attacks on non-whites in recent years, including an explosion at the Cherkizovsky market in northeastern Moscow August 21, which killed 11 people and injured at least 49. St. Petersburg has also been a focus for race-hate attacks: in September, an Indian student was stabbed to death in the city, and a Sudanese national was attacked.