A look at recent major attacks attributed to the radical Islamic extremist network known as Boko Haram:
— April 19, 2013: Fighting between Boko Haram fighters and Nigeria's military kills at least 185 people in Baga, a fishing community in Borno state in northeast Nigeria.
— Jan. 20, 2012: Boko Haram claims responsibility for a series of coordinated bombings and gun battles around the city of Kano that kill at least 185 people.
— Dec. 25, 2011: Boko Haram claims responsibility for an attack on a Catholic church in Madalla near Nigeria's capital and assaults elsewhere in the country that kill at least 42 people.
— Dec. 22-24, 2011: Boko Haram members fight with police and military forces around the city of Damaturu, leaving at least 61 people dead.
— Nov. 4, 2011: Boko Haram members bomb government buildings and shoot their way through the city of Damaturu, killing more than 100 people, while bombs and a suicide attack in Maiduguri leave 4 dead.
— Aug. 26, 2011: A Boko Haram member detonates a car loaded with explosives at the United Nations headquarters in Nigeria's capital Abuja, killing 25 people and wounding more than 100 others.
— June 16, 2011: A car loaded with explosives detonates at the federal police headquarters in Abuja, killing at least two people. Police first call the attack a suicide bombing, but later deny it.
— April 9, 2011: Gunmen from Boko Haram set fire to the Maiduguri International Hotel and kill a politician ahead of local elections.
— April 8, 2011: A bomb allegedly planted by Boko Haram explodes at an election office in Suleja in Niger state, killing 16 people.
— Jan. 28, 2011: Gunmen with Boko Haram shoot and kill the leading candidate for governor in Borno state along with six others in his entourage.
— Dec. 31, 2010: A bomb allegedly planted by Boko Haram explodes at a crowded outdoor beer garden at a military barracks in Abuja, killing at least four people.
— Dec. 24, 2010: A series of bombs allegedly planted by the group explode in the central Nigerian city of Jos, killing as many as 80 people.
— Sept. 7, 2010: Gunmen with Boko Haram free about 700 inmates from a Bauchi federal prison.
— July 2009: About 700 people die after Boko Haram members riot and a security crackdown hits Maiduguri, the sect's spiritual home.