Russian authorities are dealing with another deadly suicide bomb attack, this time in the Ingushetia region.
Two policemen were killed in a town near the regional capital when a suicide bomber tried to enter a police headquarters.
Soon after explosives in a car parked nearby were detonated by remote control, injuring a chief prosecutor and three police officers.
The attacks in the town of Karabulak came a week after suicide bombings in the Moscow metro killed at least 40 people.
Another blast in Dagestan on Wednesday killed a further 12 people.
Russian leaders have vowed to destroy Islamist militants in the North Caucasus, who have claimed responsibility for the bombings.
The attacks have fueled concern that further strikes against major Russian cities are being planned.
The insurgents are demanding the formation of an Islamic state in the Caucasus.