At least 17 people were killed and 24 others injured during a shooting Monday at School No. 88 in Izhevsk, Russia.

Authorities said 11 children were killed in the attack, as well as a school security guard and two teachers.

The gunman has been identified as Artyom Kazantsev, 34, a former student at the school. Kazantsev was a patient at a local psychiatric facility, and arrived at the school wearing a black T-shirt with “Nazi symbols” on it, Russia’s Investigative Committee said. After the attack, Kazantsev died by suicide.

This was the act of a “terrorist,” Kremlin spokesman Dmitry Peskov said. An investigation has been opened into how the suspect acquired two non-lethal handguns found at the scene that had been modified to fire bullets.

Izhevsk is in central Russia, and is the capital of the Udmurt Republic. Compared to the United States, school shootings are rare in Russia, but “may be becoming more common, with three mass shootings at educational institutions since May last year,” The Washington Post says.