At least 13 people were killed, including seven children, when a gunman opened fire at a school in the city of Izhevsk in central Russia on Monday, and President Vladimir Putin condemned it as an "inhumane terrorist attack."

Kremlin spokesman Dmitry Peskov told reporters, "The president deeply regrets the death of adults and children in this school where a terrorist attack took place."

The Russian Investigative Committee said in a statement, "Preliminary information indicates that 13 people were killed in this crime, including 6 adults and seven minors, and 14 children and seven adults were injured," confirming that the shooter committed suicide.

The Kremlin added, "The president wishes a speedy recovery to those injured in this inhumane attack."

Investigators reported that the suspect "was wearing a black shirt with Nazi symbols and a mask."

They confirmed in a separate statement that the shooter "was a former student of the school named Artyom Kazantsev, born in 1988." They added, "We are investigating to determine whether he was an adherent of neo-fascism and Nazi ideology."

Earlier reports indicated nine dead, including five children, according to the Russian Investigative Committee.

Investigators released a video showing a man's body lying on the ground, blood around his head, wearing a black shirt with a red swastika.

The Russian Interior Ministry earlier reported six dead and 20 wounded.

The ministry stated, "Police officers found the body of the shooter. Our information is that he committed suicide."

The shooting occurred in the morning at School No. 88 in the city of Izhevsk, located west of the Ural Mountains, the border between European Russia and Asian Russia.

This city still hosts factories for Kalashnikov assault rifles.

Regional governor Alexander Brechalov said the attacker "killed a security guard" before opening fire inside the school.

The school's site indicates it has about a thousand students and 80 teachers.

Brechalov added in a video from in front of the school, "The evacuation process has ended," and "the entire area has been sealed off," explaining that the Russian National Guard, security services, and "authorities responsible for the investigation" are on site. Behind him, medical teams were hurriedly entering the building, some carrying stretchers.

The Ministry of Health confirmed the deployment of "14 ambulance teams" on site, and a "group of doctors" is expected to head to Izhevsk soon "to assist the victims."

An investigation was immediately opened for "murder" and "illegal possession of weapons" and was assigned to the Russian Investigative Committee, the country's main investigative body.

The number of deadly shootings in Russia has increased, especially in schools, over the past few years, whereas they used to be very rare, to the point that it concerns President Vladimir Putin, who considered them an imported phenomenon from the United States and a negative effect of globalization, which led him to tighten gun laws.

In April, a man opened fire in a kindergarten and killed two children and a teacher before committing suicide in the Ulyanovsk region in central Russia as well.

The deadliest shooting in the country occurred in October 2018 when a student killed 19 people at a high school in Kerch in the Crimean Peninsula annexed by Russia before killing himself.

Izhevsk has a population of 650,000 and is the capital of the Udmurt Republic in central Russia.

In this industrial city, which was closed for a long time to foreigners during the Soviet era, Mikhail Kalashnikov developed the first AK-47 rifle model in 1947, which has become famous worldwide since then.