Residents in northeast Nigeria say at least 13 vigilantes and five Boko Haram members have been killed after the group launched attacks on a town.
Sunday's attack in Benisheik, 72km west of Maiduguri, took place days after the military said it killed at least 50 fighters in an area to the north.
Zannah Fannami, an injured operative with the Civilian Joint Task Force, said they were attacked while awaiting Boko Haram's approach on the town.
He said the vigilante group was able to kill five suspected members of the armed group. Another Civilian-JTF operative, Muhammed Abuwar, said the military did not assist the vigilantes and 18 others were injured.
Al Jazeera's Yvonne Ndege, reporting from Abuja, said it was unclear why Boko Haram might have attacked the town except for the fact that they might have known it was being guarded by citizens and not the military.
Ndege said the recent spike in attacks had not prompted any comment from the military regarding consolidating security in the northeastern part of the country.
The military has agreed to support any missions by the Civilian-JTF until its newest 7th Division fully formed to fight Boko Haram is fully functional.
The spokesman for that division, Lieutenant Colonel Sagir Musa, said that brigade troops were sent to the area and "the attack was repelled".
Troops are still searching for fleeing insurgents, he said.
There has been a rash of attacks by suspected Boko Haram members in northeast Nigeria recently, after young vigilantes formed the Civilian-JTF in June.
The vigilante force claims credit for thousands of arrests in Maiduguri and many killings.
More than 160 people were killed in violence linked to Boko Haram last month - one of the bloodiest periods since President Goodluck Jonathan declared a state of emergency and a military crackdown in three northeastern states in mid-May.
Since 2009, an estimated 3,600 people have been killed in an insurgency launched by Boko Haram, which says it wants to establish an Islamic state in the northeastern part of the country.
While the group has repeatedly attacked schools, churches, mosques and markets, state institutions like police stations and military facilities have remained primary targets.
Source: Al Jazeera and agencies