The terror group Boko Haram has claimed responsibility on Tuesday for a massacre in northeastern Nigeria, and their leader claimed that God commanded them to carry out the killings.

The United Nations reported that more than 7,500 people fled the Jan. 3 assault on the town of Baga on Lake Chad. Robyn Dixon of the Los Angeles Times noted that Boko Haram's leader, Abubakar Shekau, claimed in a YouTube video that the devastation of Baga was the stepping stone for bigger attacks.

"We are the ones who fought the people of Baga, and we have killed them with such a killing as he [God] commanded us in his book," Shekau said. "This is just the beginning of the killings. What you've just witnessed is a tip of the iceberg. More deaths are coming."

According to the Los Angeles Times, the 35-minute video also showed Shekau burning Nigeria's flag and declaring the country's constitution dead. His men also fired automatic weapons into the air, yelling "God is great" in Arabic.

"This will mark the end of politics and democracy in Nigeria," he said.

David Blair of the Telegraph reported that in the video, Shekau was shown wearing a camouflage jacket, complete with an assault rifle across his chest. The video also contained Arabic subtitles, given that he spoke in a rudimentary manner.

The leader of Boko Haram also dared the "kings of Africa" to get him, according to the Telegraph.

"The kings of Africa - you are late!" Shekau boasted. "I challenge you to attack me even now: I'm ready."

Baga, which was razed by Boko Haram, was supposed to be the headquarters of a strong regional force comprised of 2,800 troops from Nigeria, Niger, Chad and Cameroon. The Los Angeles Times reported that these countries signed an agreement a month before to deploy a force to take out the terrorist group; however, only the Nigerian forces were left to confront them on their own, undermining trust from the local population.

"When Boko Haram seized Baga, it took over the military base, along with weapons and ammunition," Dixon wrote. "Shekau flaunted an arsenal of sophisticated weaponry in the YouTube video and said he was ready for any attack."

Blair reported that satellite photos from Amnesty International indicated that large areas of Baga were razed to the ground. The Los Angeles Times could not gather an accurate count of how many were killed in the massacre, but the range fell "from several hundred to 2,000 people."

To date, Blair reported that Boko Haram fighters have control over 20,000 square miles of northern Nigeria, and the group's leader established its headquarters in a town near the Mandara Mountains.

"From this secure domain, Boko Haram now ranges across large areas of Nigeria and neighboring Cameroon," Blair wrote. "Hundreds of thousands of people have fled their attacks."

Blair added that the Nigerian army has made "no serious effort" to retake the lost territory from Boko Haram.