Updated

Witnesses say Boko Haram extremists have attacked a Nigerian town and killed 11 people who had just returned home after the military reclaimed the town.

Resident Mohammed Umara said troops from Cameroon immediately crossed the border and repelled Wednesday's assault on Gamboru-Ngala within an hour.

Umara and other residents have crossed the border to Cameroon.

Nigerian officials this week said they have taken back 37 towns and forced Boko Haram out of all but three local government areas of northeast Nigeria. The extremists seized Gamboru in November and were dislodged on Feb. 4.

The offensive is expected to take back territory and reduce Boko Haram to hit-and-run attacks.