Police in the Russian republic of Dagestan say at least one person has been killed and 11 injured in a live grenade accident at a high school.

The police said in a statement on Monday that they detained a teenager who brought the grenade to school in the rural area in Russia's North Caucasus. At least three teenagers are in intensive care. The police in Dagestan called it an accident but the circumstances of the explosion were not immediately clear.

Following two separatist wars in neighboring Chechnya, an Islamic insurgency spread to Dagestan where shootouts between the militants and police are almost routine occurrences and the illegal ownership of weapons is high.