A man armed with a knife and believed to be wearing a fake suicide belt went on a stabbing spree in the Russian city of Surgut, Siberia, injuring seven pedestrians. The attacker was shot dead by police after the attack happened at around 11.20am local time on Saturday 19 August.
The Islamic State group claimed responsibility for the attack hours later, but investigators are still probing whether the motive was truly terror-related after looking into possible mental health difficulties. Isis has a history of claiming incidents to which it is unconnected.
The attacker "carried out attacks on passers-by, causing stab wounds," Russia's Investigative Committee said, adding that armed police then killed the attacker. The suspect was described as a local man born in 1994. An official told the Russian Interfax news agency that terrorism was not investigators' main theory.
There have been no reported fatalities among the victims, but those hurt did require urgent medical treatment having suffered injuries of "varying severity", officers said.
A video posted online appears shows the aftermath of the attack, with a police officer seen crouching over the body of the suspect.
A second clip taken later appears to show a blanket over where the suspect's body had been, with police investigating the scene.
Images published by The Siberian Times show the suspect's dead body and what appears to be a fake suicide belt strapped to his waist.
Surgut is a city in the Khanty-Mansi Autonomous region with a population of around 350,000. It is a major centre for oil and gas production in the country and lies about 2,100 kilometers (1,300 miles) northeast of Moscow.
The attack comes the day after a mass stabbing in the Finnish city of Turku, which killed two people and injured eight others. Finnish police are treating the incident as a terrorist attack, with an 18-year-old Moroccan citizen currently in custody after being shot at the scene.