Escalating violence across the largely Muslim North Caucasus led the Kremlin last month to call the region its biggest domestic problem.
The heart of the violence is in tiny Ingushetia, where political analysts say Islamist fighters and law enforcement officers are effectively at war.
"Right now there are 23 injured, 10 of whom are ordinary citizens," state-run RIA-Novosti agency quoted investigators as saying of the attack in Ingushetia's major city of Nazran.
Three children were among the injured, investigators added, and four of the injured were in critical condition.
In August, a suicide bomber killed 25 people and wounded more than 100 at a police headquarters in Nazran, in the bloodiest attack to hit the North Caucasus since 2005.
Interfax news agency, citing Ingushetia's prosecutor Yuri Turigin, said a Lada car with a license plate from nearby Chechnya blew up in today's attack.
"A military column was driving by. All transport vehicles were ordered to stop to let the column pass...then a Priora [Lada] with a Chechen license plate whizzed by and an explosion happened," Turigin said.
In neighboring Chechnya, where Moscow has fought two wars against separatists since the mid-1990s, four men suspected of being Islamist fighters were killed by police earlier today, Interfax said, citing the Chechen Interior Ministry.
Also today, the Russian Interior Ministry said more than 600 terrorist acts were registered in Russia in the first nine months of this year, slightly up on last year, RIA reported.
- Radio Free Europe / Radio Liberty
- © RFE/RL, Inc. All Rights Reserved.