A man walks in a corridor at Russia's large Investigative Isolator detention center, which was under construction in St. Petersburg on October 17, 2014. Reuters

A group of 15 Russian convicts went to extreme lengths in a protest on Wednesday, May 27, by cutting their wrists aboard a train to a northern prison colony, the Moscow Times reported. The incident marked the second time this month that Russian prison inmates have resorted to slashing their wrists in protest.

The train was reportedly taking the prisoners from the centrally located city of Vologda to a prison colony in the Republic of Karelia in northwest Russia. The train was forced to stop at St. Petersburg's Ladozhsky Station -- about 404 miles away -- after the prisoners cut themselves. Two of the prisoners were reportedly hospitalized. It is unclear why the protest took place, with some media suggesting that the convicts were unhappy with the prison colony destination, according to the English-language Moscow Times.

Russian prisoners have previously resorted to harming themselves. A little more than a week ago, more than 30 Russian prisoners cut their wrists in protest. The incident took place at the Vozhayevka Correctional Facility No. 2, in Russia's far eastern Amur region, reported the Moscow Times. A prison system statement said the prisoners made "insignificant cuts" to their arms during a "riot." The statement said the unrest occurred after staff used force to restrain an inmate who would not return to solitary confinement after he was allowed out to exercise.

One particularly high-profile case of Russian prisoners harming themselves happened in June 2005. About 260 prisoners cut their necks and wrists to draw attention to alleged poor conditions and mistreatment, reported the BBC in 2005. The protest was carried out with great organization, with inmates in 10 sections of the prison cutting their wrists simultaneously, investigators said. The prisoners’ injuries were not life-threatening.