Boko Haram killed 110 farmers just outside the capital of Borno State in northeastern Nigeria on Nov. 28 in what is believed to be the deadliest civilian attack carried out by the jihadist terrorist group in 2020.

The farmers were working on their fields when a group of armed men riding on motorcycles attacked them, tied them up, and slit their throats, a report from The Guardian said. Some of the farmers were shot dead, according to the International Christian Concern.

Others were taken captive by the militants.

"There are also believed to have been some people who were [taken captive] in the attacks," Todd Nettleton of Voice of the Martyrs said, according to Mission Network News.

The victims were farmers who came from northwest Nigeria and traveled to the northeast side in search for work.

It was not clear at first which of the two Boko Haram factions were responsible for the brutal murders. However, the group of Abubakar Shekau claimed responsibility in a three-minute video posted on social media on Tuesday.

The Abubakar Shekau faction often attacks civilians who do not adhere to the Sharia law. The other Boko Haram faction, known as the Islamic State West Africa Province, is known to target mostly the military and the government.

According to the video, the militants admitted they were "responsible for what happened around Maiduguri in recent days ... especially in Zabarmari," a report from Deutsche Welle said.

The attack was done in retaliation to the farmers for cooperating with the Nigerian military and surrendering one of the group's members to the authorities.

The group said they killed the civilians because "the farmers arrested and handed one of its brothers to the Nigerian Army."

"You thought you would apprehend our brethren and hand him over to the military and live in peace?" the group said in the video.

Edward Kallon, the United Nations Resident Coordinator and Humanitarian Coordinator in Nigeria, condemned the terrorist attack and described it as "the most violent direct attack against innocent civilians this year."

He called for justice to be brought upon the militant group behind the massacre.

It took the authorities a few days to finish conducting a body count of the victims. A member of the search team said their vehicles could not pass through the difficult terrain. They also took extra caution because militants operate in the area.

Some governors in Nigeria feared the country could be consumed if nothing is done about the insurgency problems in the country.

Kayode Fayemi, governor of Ekiti State, admitted the military has been overwhelmed in its fight against insurgency, local media outlet Premium Times said.

Meanwhile, Nigerian President Muhammadu Buhari also condemned the Saturday attack and gave all the support needed so the armed forces could "take all necessary steps to protect the country's population and its territory."

Boko Haram has killed at least 36,000 people in Nigeria since it began its operation in 2009. Two million residents have been displaced because of the group's actions.