Seven people have been killed and 16 critically injured in a bomb attack in the southern Russian city of Stavropol.
The bomb, which was disguised as a juice container, exploded just before the start of a concert by a dance company linked with Kremlin-backed Chechen president Ramzan Kadyrov last night.
A Stavropol doctor told Rossiya-24 television that 16 people were in an "extremely grave condition" with chest, abdominal and head wounds.
Russia said investigators had opened a criminal case under terrorism laws after the attack in the ethnically Russian Stavropol region, which borders the mainly Muslim republics of the North Caucasus.
Islamist militants have vowed to expand a campaign of shootings and bombings to Russian cities. Suicide bombers on the Moscow metro in March killed 40 people in the worst attack on the Russian heartland since 2004.
Last year, Russian president Dmitry Medvedev ordered that the Stavropol region be included in a new North Caucasus Federal District along with mainly Muslim Chechnya, Dagestan and Ingushetia in a bid to tackle growing violence.