Maiduguri - As many as seven suicide bombers, six of them women, tried to attack the northeast Nigerian city of Maiduguri but only blew themselves up, emergency services officials said on Friday.Initial reports from the city had suggested a number of people were killed in the blasts near the Muna camp for displaced people shortly before 22:30 GMT on Thursday.But Mohammed Kanar, from the National Emergency Management Agency (NEMA), said there were no civilian or military casualties, as the would-be bombers arrived after the 22: 00 GMT curfew."People were indoors. There was no one on the streets," Kanar, who is NEMA's northeast coordinator, told AFP."None of the six female bombers succeeded in their attacks. They ended up being killed in the explosions," he said.A man who dropped them off in his car then tried to ram a military checkpoint was also unsuccessful. "He died in the process," added Kanar.Hamed Satomi, from the Borno state emergency management agency, gave a similar account, although he said there were only six bombers.Both organisations were involved in the recovery of the bodies, they said.The Borno state police had earlier said only one bomber was involved and that he had detonated his explosives among 13 trucks waiting to travel to the east of the state near the Cameroon border.Spokesperson Victor Isuku attributed the multiple explosions heard in Maiduguri to soldiers shelling suspected Boko Haram fighters outside the city limits.The attempted attacks came after the departure of a high-ranking delegation of foreign officials to Maiduguri as part of efforts to secure greater funding to help those made homeless by the conflict.Reports from the city also said a number of Nigerian air force aircraft were shot at in the remote region on Thursday.The incidents underline the continued threat from Boko Haram, which Nigeria's military maintains is in disarray after nearly eight years of fighting and at least 20 000 deaths.Despite the insistence the Islamist group is "technically defeated", there have been multiple suicide bombings against civilian targets, as well as attacks on police and soldiers.The thousands of people living at the Muna Garage camp are especially vulnerable, given the lack of security and easy access to the site.