MOSCOW — Three Russian journalists investigating the activities of a private security company with murky Kremlin connections have been killed in the Central African Republic, the Russian authorities said Tuesday.

The Russian Foreign Ministry said in a statement that the three Russians had been identified by their ID cards as Orkhan Dzhemal, Aleksandr Rastorguev and Kirill Radchenko. Russian investigators said they had opened a criminal case to look into the deaths.

The journalists were making a documentary about the mysterious activities of a group of paramilitary mercenaries in the Central African Republic, which is undergoing brutal sectarian strife.

There was no indication that the killings were connected with the documentary project. The assailants were not identified.