The terrorist organisation Boko Haram launched an attack against neighbouring Chad for the first time this week. 

An army spokesperson reported that the militants crossed Lake Chad in motorboats and attacked a village.

According to Chadian Colonel Azem Bermandoua Agouna, one soldier and a village chief were killed, and four civilians in Ngouboua were wounded before the Chadian military launched an airstrike and pushed the militants back. 

Agouna would not confirm other civilian casualties, but told BBC's Thomas Vessy that two Boko Haram fighters were killed and five wounded in the firefight. 

Two-thirds of Ngouboua's homes were burned, according to residents, and about 30 militants were involved. 

"They came on board three canoes and succeeded in killing about 10 people before being pushed back by the army," one witness told Reuters.

The Sunni Muslim extremists have led a reign of terror across Nigeria with increasing brutality over the past five years, with kidnappings, suicide bombings, and mass executions leaving thousands dead and millions displaced. 

Boko Haram's offensive against Chad was in retaliation for the central African country joining a coalition opposing the group with Nigeria, Cameroon, and Niger in January.

Boko Haram leader Abubakar Shekau denounced Chadian President Idriss Deby in a video released shortly after the announcement, and declared war on the country. 

BBC reported that civilians in the neighbouring countries have not joined up with the Nigerian-based terrorists, stifling the group's goal of creating a caliphate. 

Attacks in Nigeria have continued, with at least 21 people killed in two attacks in Borno State on Thursday.