Jan. 9, 2014  -- Russian security forces launched an aggressive "anti-terrorism sweep" today after coming across multiple unexplained deaths and explosive devices in a region near Sochi, where the Winter Olympic Games will be held in a matter of weeks, according to Russian news reports.

A car with a body inside exploded as police approached it in Russia's Stavropol Territory, reported Russia's state-owned RIA Novosti, citing the Interior Ministry. In the same area, Russian authorities reportedly discovered a car containing the bodies of three men along with explosive material. The day before, two more bodies were found in cars the same region.

All of the victims appear to have been shot, according to a Russian security official and international news reports. Two were taxi drivers and another reportedly worked assembling furniture.

Russian officials are investigating the possible cause and motive for the deaths -- a Russia analyst speculated to ABC News the deaths could be related to organized crime -- but at any rate the mystery and the security sweep add to an already tense situation in southern Russia as the Olympics approach.

Just 10 days ago more than 30 people were killed in dual suicide bombings in Volgograd, Russia, some 400 miles northeast of Sochi. By comparison, Moscow lies more than 850 miles north of Sochi. In October seven people were killed when a suicide bomber detonated explosives on a bus, also in Volgograd. The Stavropol Territory lies approximately halfway between Volgograd and Sochi – approximately 150 miles away from the Olympic site.

No group has publicly claimed responsibility for the bombings, but in the case of the October bus bombing, Russian authorities said the bomber hailed from Dagestan, a restive region in southern Russia to Sochi's east that, along with Chechnya, is home to a violent Islamist insurgency that has fought Russian government forces for decades.

The leader of the insurgency, Doku Umarov, sometimes referred to as "Russia's Osama bin Laden," last June called on his followers to "do their utmost to derail" the Sochi Olympics, which he called a "satanic dance on the bones of our ancestors." In the past Umarov has claimed responsibility for deadly attacks on Russian civilians, including the 2011 bombing of Moscow's Domodedovo airport.

Analysis: 2014 Sochi Olympics in Terrorists' Crosshairs

The Russian government has assured the international community that the Olympics will be safe, but according to Frank Cilluffo, director of the Homeland Security Policy Institute, and Michael Downing, Deputy Chief of the LAPD's Counter-Terrorism Bureau, some top U.S. officials are wary and are not satisfied with Russia's openness to anti-terrorism assistance from the West.

In a statement of condolences from the White House over the most recent Volgograd bombings, President Obama's National Security Council slipped in an apparent jab at the Russian government over the security situation.

"The U.S. government has offered our full support to the Russian government in security preparations for the Sochi Olympic Games, and we would welcome the opportunity for closer cooperation for the safety of the athletes, spectators, and other participants," the NSC statement said.

At the time, the Russian Embassy to the U.S. in Washington, D.C. denied Russian security services were not playing nice with their international partners.

"Russia is fully cooperating with all interested law enforcement agencies including those from the U.S.," the embassy said in an emailed statement to ABC News. "We are sure that [the] Sochi Olympic Games will be held in a secure and peaceful atmosphere."

FBI Director James Comey told reporters today that he has personally been in contact with Russian authorities and said the FBI will have a contingent of specialists on the ground at the Games available to assist Russian security forces if called upon. Today Comey described the Russians as being cooperative with the West in their security operations.

Additionally, the U.S. ski and snowboard team this year will be overseen by a private security firm, which plans to have as many as five aircraft on standby in case of a medical or security emergency in Sochi.

"This environment is unique,'' Global Rescue CEO Dan Richards told USA Today Wednesday. "You just don't have competitions in places like Sochi with any frequency. … In the last 10 years, there has been nothing like it.''

William Rathburn, who was the head of Olympic Security during the bombing of the 1996 Olympic Games in Atlanta, Georgia, told ABC News that while he's confident Russian officials "have done everything they can" to secure the upcoming games, the odds of an incident are "very high."

"It's an opportunity for the Chechen [militants] or anyone else to embarrass Russia or [Russian President Vladimir] Putin, I think," he said. "It's far easier to protect against attacks on somebody who might be targeted, a group or country or delegation. [But] it's clear that the people who conducted the two bombings in Volgograd are willing to indiscriminately kill people. It's very difficult to protect against…"

The Russian Embassy in Washington, D.C. did not immediately return an emailed request for comment for this report.

ABC News' Randy Kreider and Dragana Jovanovic contributed to this report.

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