At least one teenager was killed and 11 others injured in a blast in Russia's Republic of Dagestan, where an explosion went off at a local computer room. The incident was caused by a grenade brought into the building by one of the teenagers.

At least three of the injured teenagers are in a critical condition, RIA Novosti reported, citing a local hospital.

Dagestan's Interior Ministry spokesman confirmed the numbers of the dead and injured to RT.

Investigators are now working at the scene, the official said, adding that anti-terrorist committee is not involved in the case. According to preliminary data, the incident happened due to “careless handling of a weapon,” he told RT.

The incident happened in the village of Agvali, Dagestan, in Russia's North Caucasus region.

A grenade exploded in a computer room, RIA Novosti cited the principal of a local school, Shamil Abakarov, as saying.

The weapon was allegedly brought into the building by an eighth-grade student, he said.

только что в Цумадинском районе в агвали взорвали гранату,ждем следственный комитет ,есть раненные,Гранату РГО взорвали,трое тяжелые !всего восемь говорят!взрыв возле игрового зала,на улице кади Абакарова.Один скончался A post shared by 🔴ОФФ ПОРТАЛ ДАГЕСТАНА🔴 (@dagsity) on Apr 24, 2017 at 7:23am PDT

The ministry confirmed that the student who brought the grenade had been detained.

Police have been working with the teenager, assisted by psychologists, Russia's Investigative Committee said in a statement. The student explained that he had found the grenade in the street and then brought it into the computer room, it added.