At least three people were killed and six others injured on Friday by suicide attacks in northeast Borno state of Nigeria, vigilantes told Agence France Presse.
Two young men who refused to be searched by vigilantes blew themselves up at a security checkpoint in a village of Biu district, 180 kilometers from capital Maiduguri of Borno, killed two vigilantes and injured four people.
Mustapha Karimbe, a civilian vigilante from Biu said, "Three people, including two of our colleagues, died in two suicide blasts in Sabon Gari and Kimba villages."
Civillian vigilantes have been created to assist the Nigerian military in fighting against Boko Haram.
A checkpoint in Biu district was set up by vigilantes following intelligence report about a possible Boko Haram attack, Karimbe said.
Two young men who refused to be searched when the bus they were travelling in was stopped at the checkpoint detonated their explosives as two vigilantes accosted them, Karimbe said.
About an hour before this explosion, a bomb attack was carried out by a female bomber, when she was shot by a soldier at the checkpoint, but no one was hurt.
Biu and neighbouring villages have been repeatedly hit by Boko Haram attacks.
According to an Amnesty International report released on September 30, at least 1,600 people have been killed in violence carried out by Boko Haram since the start of June, rising the civilian death toll to some 3,500 in 2015.
Since 2009, the group has killed at least 17,000 people mostly in Nigeria and 2 million people have been displaced by Boko Haram terror.