Twin blasts rocked Russia's North Caucasus region of Dagestan on Wednesday, killing at least 12 people, just two days after two metro suicide bombings in Moscow.
Russian Prime Minister Vladimir Putin said at a government session on Wednesday he did not rule out that a single terrorist group may be behind the bombings. President Dmitry Medvedev also said there may be a link.
Wednesday's attacks took place in the town of Kizlyar, near Dagestan's border with Chechnya, and also left 29 people injured.
The first blast went off at 08:45 Moscow time (04:45 GMT), when a car bomb was detonated by a suicide bomber some 300 meters from the buildings of the Interior Ministry, Federal Security Service and a school. It had a force of up to 200 kg of TNT.
Two police officers were killed in the explosion, which also injured several bystanders.
The second explosion came 20 minutes later when a suicide bomber dressed in a police officer's uniform blew himself up as a crowd gathered.
The suicide bomber, who had the equivalent of 1.5 kg of TNT strapped to his body, has been identified as Daud Jabrailov, a citizen of Kizlyar, Dagestan's Interior Ministry said.
"Around 20 minutes later a suicide bomber, dressed in a police officer's uniform, arrived at the scene where an investigation group was working, and activated an explosive device he had on his body," the statement added.
A total of nine policemen were killed in the blasts, including the city's police chief, Vitaly Vedernikov.
Tatyana Batsina, who works around 800 meters from the scene of the attacks, told RIA Novosti that she heard a loud bang and saw a cloud of smoke rise from behind a nearby school.
"It looked like a nuclear explosion," she said. Around half an hour later she said she heard another blast, this time more muted.
"Two cars driving past were also damaged in the explosion. A crowd gathered around the first explosion. Everyone wanted to see what had happened. Several ambulances arrived, and then another blast rang out."
Batsina said a colleague who saw the explosion told her what had happened.
"Bodies that were caught in the epicenter of the explosion were strewn over the street. The blast tore off the roof of the school and broke the windows. The walls of the building shook," Batsina said.
The president of Dagestan, Magomedsalam Magomedov, left the capital, Makhachkala, to visit the scene of the attack.
Russian Interior Minister Rashid Nurgaliyev gave orders at a meeting of the Interior Ministry to step up security in areas of strategic importance and crowded public places in Dagestan.
"I ask you to be on alert," he said.
The blasts occurred just two days after two deadly suicide bombings hit the Moscow metro on Monday, killing at least 39 people and injuring dozens more. The attackers struck the Lubyanka and Park Kultury stations about 40 minutes apart during the morning rush hour.
The Moscow attacks are believed to have been committed by terrorists from Russia's North Caucasus region.
Russia has been fighting militants in the North Caucasus for almost two decades, including two brutal wars against separatists in Chechnya. Analysts suggested that Monday's attacks were revenge for a recent police operation that saw the deaths of over 20 radical Islamic fighters.
While no group has yet claimed responsibility for the attacks, there has been speculation that they may be linked to the death of the North Caucasian warlord, Alexander Tikhomirov, also known as Said Buryatsky, in an anti-terrorist police sweep earlier this month.
Tikhomirov was involved in the derailment of an express Moscow-St. Petersburg train in November, in which 27 people died.
The leading Russian business daily Kommersant said Tikhomirov was personally involved in training around 30 suicide bombers, nine of whom had already carried out suicide attacks.
MOSCOW, March 31 (RIA Novosti)