Russia was Tuesday set to question the sole survivor of a deadly police raid outside Moscow that authorities said had prevented a major attack in the capital.

The operation in the Moscow region town of Orekhovo-Zuyevo took place shortly after twin car bombs killed four and injured more than 40 in the Dagestan region, a province bordering Chechnya to the east.

"The decisive actions of the law enforcement authorities foiled an attempt to carry out a terrorist attack in the capital," the National Anti-Terrorism Committee said in a statement on its website on Tuesday.

The sole survivor of the Moscow region raid, which killed two suspected gunmen, was injured but is fit enough to be questioned, a source in the law enforcement authorities told the Interfax news agency.

"The fighter, trying to flee, jumped out of a window and broke bones. He also has a gunshot wound, but ... his state allows for him to be questioned," the source said.

"The main aim is to get information on his possible accomplices in the Moscow region and to compare it with data from surveillance ahead of his detention."

Sources in law enforcement authorities told the Kommersant business daily that the suspects uncovered in the Moscow region were members of the Islamic Movement of Uzbekistan, which is viewed as a terrorist organization by Russia and the United States.

The men had been trained in the mountainous Taliban-stronghold region of North Waziristan close to Pakistan's Afghan border, both Kommersant and the Interfax news agency reported.

One of the men was named by the Moskovsky Komsomolets daily as a native of Bashkortostan, a mainly Muslim central Russian region.

The two Boston Marathon bombing suspects with close links to Dagestan and Chechnya have focused attention on Islamist extremism in the Russian Caucasus and its links to other countries.

The highly unusual operation in the sleepy town of Orekhovo-Zuyevo, around 90 kilometers east of Moscow, saw black-clad special forces evacuate residents and use gunfire to capture three men holed up in an apartment.

Security forces found a Kalashnikov assault rifle with 25 rounds of ammunition in the apartment, the RIA Novosti news agency reported.

Over a decade after federal troops defeated a separatist rebellion in Chechnya, insurgents stage frequent attacks in nearby regions to establish an emirate in the patchwork of mainly Muslim provinces.

Russian President Vladimir Putin has ordered law enforcement authorities to ensure insurgents do not attack the 2014 Winter Olympics in the Black Sea resort city of Sochi, which is close to the North Caucasus.

AFP - Reuters