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 Nigerians were killed in the attack, said Katsina state police commissioner Abdullahi Magaji.
As the unknown group fled, they attacked a police station, he said.
Katsina has been relatively unscathed by months of violence in northern Nigeria carried out by Boko Haram Islamist militants.
They are based in the Borno state capital, Maiduguri, while there has also been a spate of recent kidnappings in southern Nigeria.
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 , reports the AFP news agency.
A visitor and a guard were killed in the attack, while a police officer was wounded, the police commissioner said.