Makhachkala: Russian security forces in Dagestan killed two men in a counterterrorism operation Sunday. Officials said one of the men was a suspect in a series of bomb attacks on local police convoys.

In a statement, the Russian National Anti-Terrorism Committee said that security forces stormed the home of two men believed to be members of a criminal gang based outside the city of Kizilyurt after the men opened fire on the police with automatic weapons, the Interfax news service reported.

The police identified one of the men as Shakhrudin Askhabov, who they said was behind a series of deadly attacks against police cars and local stores last fall who was known as “the bomber.”

Russian anti-terrorism forces continue to clamp down aggressively on rebel groups in Dagestan, even as U.S. and Russian officials have been searching for any ties between local terrorist groups and Tamerlan Tsarnaev, the older of the two brothers accused of the bomb attack at the Boston Marathon this month that killed three and injured more than 260.

The Tsarnaev family lived in Makhachkala before emigrating to the United States, and the parents of the bombing suspects have returned to live here. Tamerlan Tsarnaev, who died after being shot by the police in Watertown, Mass., and then run over by a vehicle driven his fleeing brother, visited Dagestan for six months in 2012. Investigators have been focused on that visit for any evidence that he might have been connected to an organized terrorist group.

The Russian police have killed at least five suspected rebels in Dagestan this week. Thousands of residents were evacuated from the town of Gimri, located in the mountains near Makhachkala, during a counterterrorist operation this month.