(CNN) -- Islamist militants in Nigeria's restive north have taken the lives of 34 people since Christmas, including 27 Christians attending church services.
On Tuesday, the country's military took the fight to Boko Haram's stronghold, killing 13 suspected combatants.
Joint Task Force Operation Restore Order lost one soldier during the afternoon gunfight in the isolated town of Maiduguri in Nigeria's far northwest corner, said spokesman Sagir Musa.
The task force condemned alleged Boko Haram attacks going back to July 2012 in a statement, calling them "incessant callous, brutal, barbaric and impious killings." These included attacks on mosques, churches and businesses.
Human Rights Watch said the militant group has killed more than 2,800 people in all.
On Christmas Eve, attackers raided two churches, killing 12 people and setting one of the churches alight. Six days later, suspected Boko Haram fighters killed at least 15 Christian worshipers, slitting some of their throats, according to Nigerian authorities.
Boko Haram carried out its largest known massacre in January 2012 killing 211 through coordinated bombings and gun assaults in the northern city of Kano, a popular target. The group often attacks Nigerian police stations.
The name Boko Haram means "Western education is sacrilege."
In the past, they have attacked other Muslims they felt were on an immoral path but have increasingly killed Christians.
The U.S. State Department has accused Boko Haram of attacking mosques and churches to incite tensions between the two religious groups, hoping to drive a wedge between them.
It has condemned some of the group's leaders for alleged ties to al Qaeda.
CNN's Nana Karikari-apau contributed to this report