A group of prisoners seized hostages in a jail in Russia’s southern Volgograd region on Friday and killed at least one member of staff, the country’s prison service said.

“During a session of a disciplinary commission, convicts took staff of the penal institution as hostages,” the prison service said in a statement. “Measures are currently being taken to free the hostages. There are casualties.”

A graphic video circulating on several Russian Telegram channels shows at least three hostage-takers wielding knives and standing over what appears to be injured or dead prison guards lying in a pool of blood.

One of the hostage-takers says in the clip that the group is affiliated with the Islamic State (IS). According to Shot, a Telegram channel with close ties to Russia’s security services, the hostage-takers have demanded a helicopter and $2m (£1.7m).

Russian media reported that the country’s security services were preparing to storm the building.

Russia has experienced a series of Islamist terror attacks recently, prompting questions about whether its extensive security agencies have been distracted by the invasion of Ukraine and the internal crackdown on anti-war dissent.

In March, the Afghan branch of IS, known as Islamic State Khorasan Province, claimed responsibility for a mass shooting at a Moscow concert hall, the deadliest terror attack in years, which killed 139 people.

And in June, gunmen opened fire in two cities in Russia’s north Caucasus region of Dagestan, targeting a synagogue, two Orthodox churches and a police post, killing at least 15 police officers and a priest.

The latest hostage-taking incident is likely also to raise questions about security measures within Russian prisons. It follows a similar incident this summer, in which Russian special forces freed two guards and killed six men linked to IS who had taken them hostage at a detention centre in the southern city of Rostov-on-Don.