MOSCOW A bomb blast shattered a police building in Russia's separatist Chechnya region on Tuesday and rescue workers were pulling staff from the rubble, officials said as carried by Reuters.

Three people were freed from the ruins of the building -- in Chechnya's second city Gudermes -- which houses an Interior Ministry unit fighting organized crime, said an official for the Kremlin's top spokesman on Chechnya, Sergei Yastrzhembsky.

"The three people have been taken to hospital though their condition is not known," the official said by telephone. "Two to four more people are still under the rubble and rescue efforts are continuing. This was not the first attack on the building and that shows that the unit is doing its job well."

The official said explosives had probably been detonated using a timer. Russian media also reported two mine explosions and an exchange of gunfire in Argun, east of Chechnya's devastated capital Grozny, and reported the capture of six rebels in the west of the region, including two field commanders.

The attack on the gudermes police building occurred two days after Chechnya's pro-Moscow local administration moved its headquarters from the city to Grozny.

The transfer was seen as part of Russian authorities' attempts to portray Chechnya as returning to normal, with schools and public services resuming operations nearly 20 months into the Kremlin's second military offensive in the region.