One of the four militants, killed in a special operation in Makhachkala, was identified as the leader of a local terrorist sabotage group, a spokesman for the National Antiterrorist Committee said, RIA Novosti reported.
"Alibek Abunazarov, 40, had been on the federal wanted list for a long time; according to available information, he was involved in a range of terrorist acts, deadly attacks on policemen," the spokesman said, adding that the other three militants still have to be identified.
Bomb-disposal experts are currently working at the scene, they scour the field for explosive devices, he added.
Under the antiterrorist operation, police surrounded a group of militants in a private house in Makhachkala on Friday evening. Two police officers were killed in the ensuing gunfight.
One of the terrorist attempted to break through the police cordon, but he was stopped by a policeman and set off the bomb.
The suicide bomber injured at lest 30 people, including 20 police officers.