"Two cars were blown up, the type of explosive device has not been established yet," Fatina Ubaidatova, a spokeswoman for the Dagestani police, told Reuters by phone.
The Amaq news agency, which supports the Islamic State group, posted online a statement saying its local affiliate was behind the attack.
The Amaq statement said the blast killed 10 security officers. Reuters was unable to independently verify the casualty numbers.
Islamic State has in the past said it was behind violent attacks on security forces in the North Caucasus, the volatile mainly Muslim part of Russia where Dagestan is located.
Dagestan, where Kremlin critics say widespread poverty and corruption help feed religious extremism, last saw similar attacks on police in February
Some militants in Dagestan, which borders Chechnya where Moscow led two wars against separatists in 1990s, have sworn allegiance to Islamic State.
