Islamic State inmates have taken two prison officers hostage at a jail in the southern Russian city of Rostov, the prison services announced Sunday."The inmates took two prison officers hostage" in Detention Center Number One of the Rostov region, prison authorities said in a statement."Negotiations on the release of the hostages are underway," it added.The state-run TASS news agency, citing an anonymous law enforcement source, reported that IS members who are due to appear in court on terrorism charges are among the hostage takers.Russia has been the target of several attacks claimed by the militant organization.On March 22, gunmen killed at least 144 people when they opened fire at a concert hall near Moscow in the deadliest attack on Russian soil in two decades.More than 20 people have since been arrested in connection to that attack, which was claimed by IS, including the four suspected attackers, all from the former Soviet republic of Tajikistan.