"We are alert day and night to protect our city from other suicide attacks of Boko Haram," says Modo, Fotokol member of the vigilante committee.

The Northern part of Cameroon, which mostly borders with Nigeria border, is the target of incessant attacks of Nigerian Islamist armed harassment by the suicide bombings.

Like other areas of the Far North of Cameroon, civilian groups have been organized for over a year to track Boko Haram fighters. Besides its murderous raids, Boko Haram has carried out at least 16 suicide bombings in the region, killing more than 100 people, since July.

But the results would be much higher if, in some cases, the vigilante committee members had not intervened on time. Thus, on November 9, in Fotokol, one of them, 20-year old Danna, avoided bloodshed.

"Danna spotted two suspicious young girls. He tried to neutralize with his arms, one of them, but it triggered the explosives she was carrying," Danna and two other civilians were killed, said Modo, contacted by telephone from Yaounde. "Thanks to him, suicide bombers have not come to the market as they were considering," he said.

The two suicide bombers who were from the Nigerian city of Dikwa, located 70 km from Fotokol, had spent the night before the attack with a relative, a Nigerian refugee based in the Cameroonian city.

Since 2012, the Nigerian group in Cameroon has been complicit in a system that facilitated its planning, from 2013, taking Westerners hostage, and provided arms trafficking, vehicles, and goods, according to Cameroonian security sources. In August 2014, Cameroon committed to a war to weaken the network, without being able to dismantle it.

Today, the porosity of the border, the recruitment of young Cameroonians, belonging to families of fighters in exile in Cameroon and infiltration of Cameroonian allow safe environments including Boko Haram to organize attacks, said a security source.

Suicide bombers usually depart Nigeria: once in Cameroonian territory, they easily find host families who house them. They target mainly crowded places such as markets, refreshment stands, and surrounding Mosques.

Explosives kill in general, "within 50 meters," said an officer of the Rapid Intervention Battalion (BIR), an elite unit of the army in the front-line of the fight against Boko Haram. According to him, suicide bombers are young girls and boys.

"We think that the explosives are assembled in Nigeria, with munitions recovered during attacks on military bases.

- 'Very thorough indoctrination' -

In most cases, the explosives are triggered by holders, according to the BIR officer. "Suicide bombers are generally aware of what they do" after passing through "a very thorough process of indoctrination."

Some suicide bombers act under the influence of drugs, "their leaders make them take Tramol (drug popular in several countries in the region) and the Indian hemp before sending them on a mission ordered," said the security source.

The deployment of vigilante groups is growing as Boko Haram multiplies its attacks.

These civilians usually operate with sharp objects (machetes, knives, and spears) and are closer to the Islamists, so constituting a "shield" between local jihadists and Cameroonian soldiers.

"We became like soldiers. We have been tracking the Boko Haram," said on condition of anonymity one of them, in the village of Amchide. More than 200 men of the city are engaged in the watchdog group, monitoring key access points.

Amchide was one of the epicentres of conflict between Cameroonian soldiers and Nigerian Islamists. This was before the town was recaptured recently by the Nigerian military. Police and gendarmes deserted Amchide for months. Since then, the Vigilante Committee holds police and gendarmerie.

He arrested 50 suspected Islamists since December 2014, after having developed a list of over 200 potential members of Boko Haram, who are the youth of the city, according to the group member. "This allowed us to arrest 30 in five days in August. We went into the bush to tender their ambushes.

But in return, the vigilance committees are a prime target for Boko Haram. Four of them have been slaughtered in Assighassia on November 13 by Islamists during their incursion in the Cameroonian city. Two days later, two were killed in the Limani area near Amchide.