The North Caucasus was rocked by its worst terror attack in months Thursday when a suicide attacker triggered a powerful car bomb outside a market in Vladikavkaz, killing at least 16 people and injuring 138.
The attack, which was immediately blamed on Islamist militants, coincided with a spate of suspected terrorist activity as Muslims marked the end of the holy month of Ramadan.
Authorities in Dagestan said they uncovered an improvised bomb laboratory in a hotel and an undetonated bomb at a hydroelectric station.
The bomb in Vladikavkaz blew up at about 11:30 a.m. when a Volga car parked outside one of the city's main markets exploded. The car was parked close to the market's entrance, where unemployed men gather to be hired for day labor.
Among the dead was an 18-month-old child, who was badly injured in the blast and died hours later in the hospital, Interfax reported. Another seven children suffered non-life-threatening injuries, the report said.
In all, 138 people were injured in the explosion, 110 of them were hospitalized, RIA-Novosti reported.
Television footage from the scene showed a street splattered with blood and rescue workers carrying away maimed bodies.
Only the engine and front wheels remained of the exploded Volga. The bomb contained an equivalent of 40 kilograms of dynamite, the Investigative Committee said in a statement.
The suicide bomber was believed to have been sitting in the back seat when the explosion happened, Interfax reported, citing officials in the regional Interior Ministry.
Reports that two suicide bombers were in the car remained unconfirmed, but they were echoed by North Ossetian leader Taimuraz Mamsurov, who said the Volga was moving when it blew up. "The car was not standing still. It was driving in traffic," he said, Interfax reported.
Investigators said they believed that the car was driven into North Ossetia from neighboring Ingushetia about 90 minutes before the blast. The driver identified himself at a police checkpoint by the last name of Archakov, Interfax reported, citing an unidentified law enforcement source. The source said the driver's identification papers might have been forged.
But RIA-Novosti, also citing a law enforcement source, said the driver had been identified by the last name of Archiyev.
Both officials said the car was registered in Ingushetia and the owner had been identified as a certain Dobriyev, who told investigators that he had sold the car to an unknown man.
Local law enforcement agencies were put on high alert, and Vladikavkaz's schools and kindergartens were closed.
Ingush leader Yunus-Bek Yevkurov said all markets in Ingushetia were also closed.
Yevkurov said Ingush people were also a target of the attack because many would buy food in Vladikavkaz for the end of Ramadan fasting. North Ossetia saw vicious ethnic conflict in its Ingush-populated eastern districts in the early 1990s.
President Dmitry Medvedev called the attackers "scum" and promised to capture them.
The Federal Security Service has detained three suspects, FSB director Alexander Bortnikov said, RIA-Novosti reported.
Prime Minister Vladimir Putin, who celebrated the Muslim holiday Eid ul-Fitr by meeting Russia's chief mufti, urged the country's Muslim community to join in the fight against terrorism.
Bombers have struck at Vladikavkaz markets in the past. The deadliest instance was in 1999, when a powerful bomb at the same market killed 52 people and injured about 200.
More explosions occurred in 2000, 2001 and 2002, with a combined death toll of 19.
In 2008, 12 people were killed when a female suicide bomber blew herself up in a shuttle taxi near a market in the city.
North Ossetia also witnessed the 2004 Beslan hostage tragedy, which killed about 330 people, and a deadly attack on the garrison town of Mozdok in 2003, which killed 20.
Analysts said North Ossetia and its capital were Islamist targets because of the role of the predominantly Christian Ossetians in Russia's conquest of the Caucasus. Vladikavkaz, which means "ruler of the Caucasus," has been the major foothold in the region since being founded as a fortress in 1784.
"Sadly it is only logical for them to strike here," said Andrei Soldatov, a security analyst with Agentura.ru, a think tank.
Fear of attacks also gripped Georgia. A panic broke out in the biggest market in the capital, Tbilisi, after rumors spread on Thursday afternoon that a bomb had been placed there. Crowds toppled stalls as they tried to get out of the Lilo market, Interfax reported. Police said later that a thorough search had failed to turn up any explosives.
Meanwhile, reports from Dagestan suggested that Islamists there had for the first time conducted a major attack on sensitive local infrastructure.
RusHydro said Thursday that a bomb was discovered in the Irganai plant, located in the mountains west of the regional capital, Makhachkala.
The explosives, hidden in water bottles placed next to a cell-phone detonator and equivalent to three kilograms of dynamite, were found by workers cleaning up after a fire.
The flames early Wednesday destroyed much of the plant, but RusHydro maintained Thursday that they had been caused by a combustion of lubricating grease.
Islamist rebels claimed that they carried out a bomb attack on the 400-megawatt plant. A statement on the rebel Kavkaz Center web site said militants had placed three bombs, two of which went off.
A staff member from the power station disappeared 90 minutes before the fire, and a search is under way, Interfax reported.
The power station also made headlines recently when its chief engineer was mysteriously abducted in July. Vladimir Redkin, who has worked in Dagestan's hydropower sector for more than 30 years, was freed last Friday, RusHydro said on its local web site, without elaborating.
Security in the North Caucasus' hydropower plants has been a major concern for Moscow. In July, attackers entered the Baksan hydropower station in Kabardino-Balkaria, killed two guards and planted bombs that destroyed two of the station's three generators.
After the attack, Medvedev promised to fire officials in law enforcement agencies and state companies if an attack like the one on Baksan occurred again.
Also Thursday, police in Makhachkala discovered a makeshift bomb laboratory in a hotel room after an explosion shook the room and three masked men fled into the hotel lobby, shooting a staff member and a guest before vanishing in the darkness, the official Riadagestan.ru news web site reported.
The two victims were hospitalized, the report said.
Police then discovered and defused two bombs in the room, each containing an equivalent of 1.5 kilograms of dynamite, as well as bomb-making material, handguns and a grenade.
Police uncovered a similar laboratory in a house in a Makhachkala suburb on Sept. 5, the report said.