Suspected Boko Haram Islamists have attacked four villages in north-eastern Nigeria, near a town where more than 200 teenage girls were kidnapped in April.
Militants targeted at least one church in the attacks and dozens of people are feared dead.
Residents say gunmen riding on motorcycles opened fire on worshippers and pursued them as they tried to flee into the surrounding bush.
It is understood the attackers also hurled explosives into churches as services were underway, and torched several buildings.
The four villages - Kwada, Ngurojina, Karagau, Kautikari - are in Borno state, the stronghold of the Islamist group which has killed thousands during a five-year extremist uprising. The villages are near the town of Chibok where 276 teenage girls were abducted from a secondary school on 14 April.
"The attackers went to churches with bombs and guns," Timothy James, a Chibok resident said by phone. "From what I gathered, dozens of worshippers, including men, women and children were killed," he said.
His information had come people who fled the affected area and through phone calls.
Enoch Mark, an outspoken Chibok leader since the April kidnappings, gave a similar account and said he feared the dead numbered in the dozens. According to Mr Mark, the military did not respond to distress calls after the attack began.
Boko Haram, which has said it wants to create a strict Islamic state in Nigeria's mainly Muslim north, has attacked churches throughout its insurgency.
Following the April kidnapping of the schoolgirls, from parents and local leaders accused the military of doing almost nothing to secure the release of the hostages.
Fifty-seven of the girls escaped within days of the night-time raid on the school and local officials have said that 219 are still being held.
International outrage has spread since the kidnappings and Nigeria has promised to better secure in the northeast, which has been under a state of emergency since May of last year.