GROZNY, October 10 (RIA Novosti) - One policeman was killed and fifteen people were wounded in an explosion on Friday in Grozny, the capital of the Russian North Caucasus republic of Chechnya, investigators said Saturday.

Earlier 12 people were reported wounded. There are three civilians among the wounded.

Before the explosion, militants attacked a police van with a grenade launcher, but the vehicle was empty. Officers then came to the scene, and an explosive device believed to be a landmine went off, a spokesman for the republic's investigators said.

An investigation is underway.

Russia's North Caucasus republics, in particular Chechnya, Dagestan and Ingushetia, have seen an upsurge of militant violence this year, with frequent attacks on police and officials.

Chechen President Ramzan Kadyrov, a former Chechen militant, has pledged to end a recent rise in violence in the republic. As president, he has been credited for bringing relative peace to Chechnya, which saw two Kremlin-led campaigns against separatists in the late 1990s and early 2000s.