A professor has defended his decision to continue teaching students at a Russian university amid a mass shooting that killed six people and left 28 others wounded on Monday. The suspect, 18-year-old Timur Bekmansurov, has been detained by police for opening fire at Perm State National Research University, located about 1,100 kilometer (700 miles) east of Moscow.  The students and staff locked themselves in rooms during the attack, while videos showed some jumping out of second-story windows. Amid the mayhem, Professor Oleg Syromyatnikov continued his lesson on the history of Russian literature in the campus lecture hall on the fifth floor. Quoting local media outlets, Newsweek reported that Syromyatnikov did not even allow students to get under their desks.

Syromyatnikov, however, defended his actions,  saying he had been told by his dean to “continue my lesson.” He said, after a student informed him about the shooting, he closed the metal door of the lecture hall from the inside. “It is impossible for it to be pierced with a shot,” he told the 59.ru outlet. “Would it have been better if there were panic among the students?”

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He said that jumping out of the window was not safe either and could have left students with neck injuries. “I remained calm and continued my lecture,” he added.

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The university is investigating Syromyatnikov’s actions even as the its president Vladimir Malanin said the professor had done “everything he could.”

“He decided to close a fairly solid door, and continuing the lecture, it seems to me, helped to prevent panic,” Malanin told Russia’s Kommersant daily newspaper.

Syromyatnikov, however, drew criticism from the chairman of the Supreme Council of the Russian Union of Rescuers, Alexei Dudarev, who said, “In any emergency, you must carefully evacuate the building.”

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Russia’s Investigative Committee said police shot and injured Bekmansurov who is said to have walked onto the campus in black tactical gear, entered a building and opened fire on other students. 

Minister of Science and Higher Education Valery Falkov said Tuesday that the shooting at the Perm State University on Monday was a “grave tragedy.”

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“Those who survived (I wish) the speediest recovery. Today seven kids will be transported to Moscow for treatment,” Falkov said at a memorial ceremony in Perm.

In May, a gunman opened fire at a school in the city of Kazan, killing seven students and two teachers.