After four knife-wielding inmates claiming to be aligned with the Islamic State instigated a mutiny in a Russian prison last week, resulting in the deaths of 13 people, even the Kremlin’s most loyal lieutenants raised critical questions about how it could have happened.

“Where did the prisoners get knives, flags and mobile phones in a maximum-security colony?” Aleksander E. Khinshtein, an arch-conservative member of Parliament from the ruling United Russia party, asked on his Telegram channel.

Only two months earlier, he noted, a similar revolt had taken place in another penitentiary, in the city of Rostov-on-Don in southern Russia.

“Why, given the relevance of the terrorist threat and the sad Rostov experience, has the work on preventing extremism and the spread of destructive ideas in the penal system not been brought to the proper level?” Mr. Khinshtein continued.

The uprising last week in the Volgograd region, in which all the instigators were killed, was the latest in a series of violent episodes in Russia in which Islamic extremists either claimed credit or were blamed by Russian authorities.

In the Rostov incident, in June, six detainees accused of terrorism violently took control of a detention center before all but one of them were killed. One week later, gunmen in the predominantly Muslim Russian region of Dagestan simultaneously attacked Christian and Jewish places of worship, killing 22.