MOSCOW — A gunman opened fire in a school in central Russia on Monday, killing 15 people and wounding 24 others before shooting himself dead, authorities said.

The shooting took place in School No. 88 in Izhevsk, a city 960 kilometers (600 miles) east of Moscow in the Udmurtia region.

Russia’s Investigative Committee identified the gunman as 34-year-old Artyom Kazantsev, a graduate of the same school, and said he was wearing a black t-shirt bearing “Nazi symbols.” No details about his motives have been released.

The Committee said 15 people, including 11 children, were killed in the shooting, and 24 other people, including 22 children, were wounded in the attack.

The governor of Udmurtia, Alexander Brechalov, said the gunman, who he said was registered as a patient at a psychiatric facility, killed himself after the attack.

Kremlin spokesman Dmitry Peskov described the shooting as “a terrorist act” and said Russian President Vladimir Putin has given all the necessary orders to the relevant authorities.

“President Putin deeply mourns deaths of people and children in the school, where a terrorist act took place,” Peskov told reporters Monday.

The school educates children between grades one and 11. It has been evacuated and the area around it has been cordoned off, the governor said.

Russia’s National Guard said Kazantsev used two non-lethal handguns adapted to fire real bullets. The guns were not registered with the authorities.

A criminal probe into the incident has been launched on charges of multiple murder and illegal possession of firearms.

Izhevsk, a city of 640,000, is located west of the Ural mountains in central Russia.