NAZRAN, Russia — A suicide bomber blew himself up at a police station in a restive Russian province on Monday, killing two officers and wounding two others, officials said.The bomber's car later also exploded, wounding an investigator.The attack occurred a week after two suicide bombers killed 40 rush-hour commuters and wounded 121 on the Moscow subway in the first terror attack in the Russian capital since 2004. Authorities have blamed militants from the North Caucasus.In Monday's attack in the North Caucasus province of Ingushetia, the attacker approached the police headquarters in the town of Karabulak and detonated his explosives, said regional prosecutor Yuri Turygin. The blast killed two officers and wounded two others, he said.Investigators believe the attacker had sought to target a bigger group of officers, who were lining up at an internal yard, but set off his explosive belt when the police at the entrance demanded his ID.About half an hour later, a vehicle the attacker had parked outside the police headquarters exploded, wounding an investigator of the local prosecutor's office who was part of a group of officials inspecting the area after the first blast.The explosions damaged the police headquarters and nearby residential buildings and destroyed several cars.Ingushetia and other Caucasus provinces have been plagued by regular attacks and bombings by Islamic militants who have spread around the region after two separatist wars in neighboring Chechnya.The violence sweeping the impoverished southern region is increasinglybeing described as a civil war between Kremlin-supportedadministrations and Islamic militants. Widespread abuses againstcivilians by police, including abductions, torture and killings, havehelped to swell the ranks of the militants.One of the two suicide bombers on the Moscow subway has been identifiedas the 17-year-old widow of a slain Islamic militant from the provinceof Dagestan.A Russian newspaper reported Monday that the second Moscow suicidebomber may have been a 28-year-old schoolteacher from Dagestan. NovayaGazeta quoted the woman's father as saying he recognized her in aphotograph.Dagestan, wedged between Chechnya and the Caspian Sea, was the site oftwo suicide bombings on Wednesday that killed 12 people, mostly policeofficers. Another explosion there Thursday killed two suspectedmilitants. On Sunday, two powerful explosions derailed a cargo train,but no one was injured.