Several men have been detained on suspicion of being involved in a blast in the capital of Chechnya, Grozny, a source in the Interior Ministry of Chechnya told Russian news agencies.
"There is a large group of detainees who may be involved in the terrorist act and organisation of the explosion," the source said.
According to the source, there are no exact figures on the number of those killed and injured.
At the Dynamo stadium in Grozny, an explosion went off at 10:35 a.m. According to preliminary information, an unidentified explosive device was placed in the central grandstand of the stadium, where at that moment a concert was under way on the occasion of Victory Day.
The source in the republic's Interior Ministry told RIA Novosti that "the explosive device was installed in the midst of the central grandstand. In all probability, the terrorist attack was directed against the military-political leadership of the republic, in particular the president of Chechnya, Akhmad Kadyrov," the source emphasised.