Awwal 29, 1432 H/March 4, 2011, SPA -- Authorities say a fourth person has died a day after a bomb ripped through a ruling party political rally in northern Nigeria, AP reported. Niger state police spokesman Richard Oguche said Friday that 20 people were wounded in the bombing that killed three people on the scene. The attack occurred Thursday during a rally for Babangida Aliyu, the People's Democratic Party gubernatorial candidate for the state. That party has ruled Nigeria since the country became a democracy more than a decade ago. Oguche says police are questioning suspects with hopes of finding those responsible for the attack. The blast comes as Nigeria faces a set of April elections to decide who will govern the oil-rich nation that is a major supplier of crude to the U.S. -- SPA