A German engineer abducted in January by gunmen in Kano in northern Nigeria has been killed, a security source in the city has told the BBC.It happened during a rescue bid, military officials told news agencies.Two expatriates, seized in the north-west of the country last year, died when Nigerian and British forces tried to free them in March.The latest developments came as the authorities said an Italian engineer had been kidnapped western Nigeria.Kidnappings are uncommon in the western state of Kwara. But oil workers are often targeted for ransom in the south, and Islamist militants are active in northern Nigeria, where the German engineer was seized in January.Details about the circumstances of Thursday's raid are still sketchy - police in Kano are due to brief the media later on Thursday."The German abducted in January has been killed by his abductors early this morning," a military official told AFP on condition of anonymity."Following intelligence reports, men of [a military task force] raided a hideout where he was being held by his abductors."Residents in the west of the city say they heard gunfire during the morning.A crisis team set up by Germany's foreign ministry is trying to find out further information, German news website Die Welt reports.It is not clear who was behind his abduction, but in March a video purported to be from al-Qaeda's north African wing demanded Germany free a woman jailed on terror charges in return for his release.It was obtained by a private Mauritanian news agency, ANI, which frequently publishes statements by al-Qaeda in the Islamic Maghreb.The Italian man abducted in Kwara reportedly works for Borini Prono, an Italian building and civil engineering firm that focuses mainly on roads.A government spokesman in Kwara state confirmed to the BBC that the kidnapping had occurred and said the engineer was at a work site when he was seized on Monday.An Italian foreign ministry spokeswoman said Italian officials were in contact with the Nigerian authorities and the man's family."We can confirm an Italian engineer has been kidnapped. We don't yet know why or by whom," she told the AFP news agency.