Mohammed Bomboi is in shock and mourning as he sits in a raffia hut less than a metre from where his friend was killed by one of three suicide bombers.
Local officials say 20 people died in this small fishing and farming village, though emergency workers in Borno state put the death toll at 30. Villagers say between 21-25 died.
"We were resting on that mat in this tent Sunday night when I heard a loud sound outside," Bomboi said, pointing to the sandy floor where he had slept.
"It was Boko Haram again. I saw many bodies outside as they were scattered on the road."
One target was a thatched hut in the centre of the village, where people gather after work to watch movies or gossip. On Sunday, a Women's World Cup football match had attracted a crowd.
"People usually come to watch matches in the viewing centre. One match was playing in the TV. We didn't know Boko Haram was watching us. My friend went to join them and he died," Bomboi said.
Boko Haram not far
There were three suicide bombers: an adult male and two young girls who blew themselves up among those watching football and enjoying tea at a shop along Sambisa street, named for the Sambisa Forest - the notorious stronghold of Boko Haram less than 100 kilometres away.
Villagers say the bombers mingled with them earlier in the evening before rushing into the crowd and detonating the explosives strapped to their bodies.
"Twenty persons were killed in all - one of them died in the hospital while the other 19 died here in the village. Thirty-eight persons were injured and are receiving treatment in the hospital," said Sadiq Usmobik, a police spokesman of Borno state.
The casualty figures could potentially have been higher but one of the bombers, a girl, tripped while running towards a crowd and her bomb went off early.
Usman Kachalla, head of operations at the State Emergency Management Agency, put the death toll at 30.
No group has claimed responsibility for the attack, but it has been strongly linked to Boko Haram insurgents, who are known to use children in suicide bomb attacks targeting civilians in churches, mosques, markets, schools and other small gatherings.
The UN children's agency, UNICEF, did not single out Boko Haram on Monday.
"UNICEF condemns the use of children as human bombs and in any combat or non-combat roles in the conflict in northeast Nigeria," it said in a statement.
"This incident brings the number of children who have been reported as having been used as human bombs to five since January 2019. In 2018, 48 children - including 38 girls - were used in suicide attacks."
Assaults by Boko Haram since 2009 have killed more than 27,000 people and forced two million to leave their homes.
'It was too late'
Such carnage in places such as Mandarari is not just a reflection of the ruthlessness of fighters, but also underlines the failures of the state.
Villagers say fewer people would have died if emergency services arrived more quickly, or if there were better health facilities available in the area, just 40km from Maiduguri, the state capital.
"At first his injuries were not that bad. But with time they got worse," said Awolo Abubakar, whose 30-year-old son was caught in the attack.
"So when help came, it was too late. That's why my young son, without any children of his own, is in a grave today."
Over the years, Boko Haram has evolved; moving into far-to-reach communities and dominating the lives of millions. The Nigerian military has been unable to establish order in the vast expanse of the country's northeast.
The attacks have forced many to leave their homes. Along the short trip between Mandarari and Maiduguri, vacated farm land and empty villages show the extent of the exodus.
"The current approach has failed. It's not enough to fight this war through the military alone. Good governance, economic policies and mass education are all part of the war the government has refused to fight. That's why Boko Haram is not ending soon," security analyst Nnamdi Anekwe-Chive told Al Jazeera.
"The people are disappointed in their leaders. The leaders in northern Nigeria have failed the people. It's the underdevelopment they created in the north that is helping all these crises thrive," he said.
'Can't fight back'
Another deadly crisis has also emerged in Nigeria's northwest, with more than 300 people killed this year by bandits and kidnappers.
In Mandarari, Bomboi stands over a pile of victims' shoes partially buried in the dust. The various sizes and colours reflect the diversity of those who last wore them - children, women and men.
"Boko Haram is near here" said Bomboi, "and they have continued to kill this way. They keep using some to bomb us. They keep attacking our villages and we can't fight back. It has happened many times."
The mood in the village is not just mournful, it also anticipates the future with fear.
Survivors know by living so close to Boko Haram-controlled territory it is likely attackers will again make their way into the community, along with hundreds of others in Konduga, Bama and Gwoza - all in restive Borno state.
By Orji Sunday