Four loud explosions were heard in the sky in the center of Belgorod on Wednesday afternoon - perhaps an air defense system went off, a RIA Novosti correspondent reports from the scene.

The explosions were so strong that windows in the buildings shook - presumably, the air defense system went off. There has been no official comment as yet.

The day before, an air defense system was in operation in the town of Grayvoron and Valuisky district. In addition, two people were killed in the shelling of Shebekino.