Authorities in Tatarstan apprehended a 13-year-old boy on Thursday following a knife assault that injured a janitor at a local school.

The incident occurred at Lyceum No. 37 in Nizhnekamsk, where the teenager set off firecrackers before launching an attack on the janitor. Officials reported that while the janitor sustained injuries, they were not life-threatening, and no students were harmed during the event.

According to the Investigative Committee, Russia’s leading investigative agency, the stabbing was the result of a dispute between the boy and the janitor. The teenager was later hospitalized after sustaining injuries from a flare gun he had discharged.

Police have initiated an inquiry into charges of attempted murder and negligence.

News channels on Telegram linked to Russian law enforcement suggested that the assailant may have attempted self-harm with the flare gun and that he had been subject to bullying at school.

The Moscow Times has not been able to confirm these claims independently.

Since the beginning of winter, Russia has recorded at least four knife incidents in schools. Notably, in December, a 10-year-old boy from Tajikistan was fatally stabbed by a ninth grader at a school near Moscow in what is believed to have been a racially motivated attack.