Abuja:
Following are the main attacks linked to the Boko Haram group in Nigeria since the extremist Islamists resumed major operations in 2011 after going underground for more than a year.
Violence by the group, which is demanding the creation of an Islamic state in mainly Muslim northern Nigeria, has left several thousand dead in the north and centre of the country since 2009.
Boko Haram, which was created 10 years ago, led a deadly insurrection in 2009 in the northeastern city of Maiduguri that was crushed by the army, causing more than 800 deaths in just a few days.
- November 4, 2011: A series of attacks on police targets and churches in the northeastern city of Damaturu claimed by the sect kills at least 150 people.
- January 20, 2012: At least 185 people are killed in the northern city of Kano following coordinated bombings and gun battles, claimed by Boko Haram.
- April 19, 2013: Fierce fighting between troops and suspected Islamists in the remote northeastern town of Baga kills 187 people while 77 others are injured.
- September 17, 2013: An attack by Boko Haram Islamists disguised in military uniforms in the northeastern Benisheik area in Borno state kills at least 142 people.
- February 15, 2014: An attack blamed on the sect leaves more than 100 people dead in the mostly Christian village of Izghe in Borno.
- April 14, 2014: Gunmen kidnap 276 female high school students in Chibok, northeastern Nigeria. Although 53 managed to escape, 223 are still being held.
The head of Boko Haram says he will sell them as "slaves" or marry them by force. Amid international outrage, Britain, France, Israel and the United States send experts and material assets to try and find the girls.
- April 14, 2014: A blast at a bus station packed with morning commuters at Nyanya, on the southern outskirts of Abuja, kills at least 75 people, in the most deadly attack to date on the capital. Most previous attacks have taken place in the group's stronghold in the northeast.
- May 5, 2014: At least 300 people are killed in an attack at Gamboru Ngala, a town near the border with Cameroun that is totally destroyed, local sources say.
- May 20, 2014: At least 118 dead and 56 wounded in two attacks on a market in Jos, central Nigeria. The regional governor blames Boko Haram.
In two days, almost 150 people are killed throughout the country, and a state of emergency is declared for three northeastern states.