MAIDUGURI, Nigeria — The death toll from an attack in northeastern Nigeria that saw insurgents dressed as soldiers set up checkpoints and gun down travelers on a highway has risen to at least 142, an official said Sunday.

"We recovered 55 bodies on Wednesday and 87 on Thursday," Abdulaziz Kolomi, an official with the environmental protection agency in Borno state where the attack occurred, told AFP. The previous toll from the attack in the Benisheik area was 87.

The insurgents suspected to be from Islamist extremist group Boko Haram also burned scores of homes and buildings in the assault and left corpses littering the roadside.

The motivation behind the assault was not immediately clear, but Boko Haram members have repeatedly carried out revenge attacks against residents over the emergence of vigilante groups that have formed to assist the military.

Residents said the attackers singled out people from Borno, while letting people from other regions pass through checkpoints.

Benisheik was also the scene of deadly clashes on September 8 between suspected Boko Haram gunmen and vigilantes.

Northeastern Nigeria has seen an outburst of violence in recent days, leaving scores of people dead and casting doubt over the effectiveness of a military assault seeking to end Boko Haram's four-year insurgency.