Bauchi(Nigeria): A large sack of home-made bombs discovered at an abandoned Boko Haram camp exploded, killing 63 people, witnesses said on Wednesday of a toll many times higher than in any recent attack in northeast Nigeria.

The explosives were found by civilian self-defense fighters who carried the bag filled with metal objects to the nearby town of Monguno, said fighters including Haruna Bukar. A curious crowd gathered to inspect the bag, which is why there were so many victims when it exploded, said Bukar, who witnessed the blast.

Many wounded people are being treated in the hospital, he said. "It's very sad because most of those killed and injured are young men, with a small number of females," Bukar told The Associated Press by telephone.

Nigeria's homegrown extremists use these kinds of improvised explosive devices in suicide bombings and also to set ablaze homes and buildings of which tens of thousands have been torched. At least 97 people have been killed in suicide bombings in northeast Nigeria since May 30, and 113 in the past month.

The highest toll from a single bombing was 29 who died in twin suicide bombings on June 4 in the main market at Yola, the capital of northeastern Adamawa state. Many of the people carrying bombs are women and children. A bomb disposal expert has told the AP that most suicide bombs are set off remotely, meaning the carrier has no control.

Abbas Gava, a spokesman for the civilian fighters, said yesterday's deaths were tragic. "This also further heightens our fears of the need for a lot of sweeping to be done by the explosives ordnance department before people are allowed to go back to their liberated homes," he said. Boko Haram took control of a large swath of northeast Nigeria until a multinational force this year forced them out of towns and villages. Nigeria's military says the extremists are now mostly confined to the Sambisa Forest