A group of 30 gunmen have used dynamite to force their way into a well-guarded compound in northern Nigeria and seize a French engineer, police say.Two Nigerian guards were killed in the attack, said Katsina state police commissioner Abdullahi Magaji.French President Francois Hollande said his government would do everything it could to find the unnamed engineer.Katsina has been relatively unscathed by recent violence in northern Nigeria carried out by Islamist militants.As the unknown group fled, they attacked a police station, Mr Magaji said.He told AFP news agency he did not think the Boko Haram militant group, which is based in the Borno state capital, Maiduguri, was behind the kidnapping.The kidnapped man worked for a French company on a wind power project in the town of Rimi, about 25km (15 miles) from Katsina city, AFP reports.Two security guards were shot dead in the attack, while a police officer was wounded, the police commissioner said.Earlier this year, a kidnapped German engineer was killed by his captors during a failed rescue bid. The BBC's Wills Ross in Nigeria says it is thought the group holding him had links to al-Qaeda's North African wing, which is active in neighbouring Niger, and Mali.A British and an Italian hostage were also killed this year during a similar attempt to free them by British and Nigerian forces.There has been a spate of recent kidnappings in southern Nigeria, where the motive is usually a ransom.