As per news agency's report, a car bomb with an estimated 30 kilograms of TNT exploded in the city of Pyatigorsk.
A suicide bomber blew himself up at a police checkpoint on the border between the republics of Ingushetia and North Ossetia.
President Dmitry Medvedev ordered the intelligence service to take all necessary steps to investigate the bombing.
At first the local authorities assumed that it was a gas explosion but later established that a car parked outside the cafe had been exploded.
Pyatigorsk is located near the city of Stavropol and is a region which has a mainly ethnic Russian population and is not considered to be part of the conflict area in the North Caucasus.
But Islamic extremists in the conflict regions have repeatedly threatened to expand their fight for an independent “Caucasus Emirate" to other parts of Russia.