Who are Africa’s most dangerous terror groups?

A Boko Haram flag flutters from an abandoned command post in Gamboru deserted after Chadian troops chased them from the border town on February 4, 2015. Nigerian Boko Haram fighters went on the rampage in the Cameroonian border town of Fotokol, massacring dozens of civilians and torching a mosque before being repelled by regional forces. AFP PHOTO/STEPHANE YAS (Photo credit should read STEPHANE YAS/AFP/Getty Images)

Who are Africa's most dangerous terror groups?

Deadly bombings, mass kidnappings and shocking massacres. CNN's Robyn Kriel explores the continent's deadliest terror organizations.

01:55 - Source: CNN

Boko Haram 17 videos

A Boko Haram flag flutters from an abandoned command post in Gamboru deserted after Chadian troops chased them from the border town on February 4, 2015. Nigerian Boko Haram fighters went on the rampage in the Cameroonian border town of Fotokol, massacring dozens of civilians and torching a mosque before being repelled by regional forces. AFP PHOTO/STEPHANE YAS (Photo credit should read STEPHANE YAS/AFP/Getty Images)

Who are Africa's most dangerous terror groups?

01:55

Now playing

- Source: CNN

boko haram captives freed nigeria army sevenzo nr_00003325

Nigerian army frees 1,000 Boko Haram captives

02:19

Now playing

- Source: CNN

Aishat Alhaji , one of the kidnapped girls from the Government Girls Science and Technical College Dapchi who was freed, is photographed after her release, in Dapchi, Nigeria, Wednesday March. 21, 2018. Witnesses say Boko Haram militants have returned an unknown number of the 110 girls who were abducted from their Nigeria school a month ago. (AP Photo/Jossy Ola)

Tears as captured schoolgirls return

01:00

Now playing

- Source: CNN

03 nigeria missing girls dapchi

The search for Nigeria's missing school girls

02:16

Now playing

- Source: CNN

Nigerian school girls missing cnni screengrab

Girls missing after raid on Nigerian school

01:07

Now playing

- Source: CNN

Soldiers stand guard at a market in N'Djamena following a suicide bomb attack on July 11, 2015. At least 14 people were killed in a suicide bomb attack at a crowded market in Chad's capital today just days after Boko Haram claimed a previous bombing in the city that left 38 people dead. The attack in N'Djamena by a man disguised as a woman in a full-face veil came after a botched bombing of a bus station in the restive capital of Nigeria's Borno state, Maiduguri, which killed two pedestrians. AFP PHOTO / BRAHIM ADJI (Photo credit should read BRAHIM ADJI/AFP/Getty Images)

Deconstructing Boko Haram's bombing tactics

02:49

Now playing

- Source: CNN

chibok schoolgirls reunited sot_00010928.jpg

Chibok girls reunited with their families

01:16

Now playing

- Source: CNN

ishay sesay nigeria chibok girls rehabilitation pkg_00005716.jpg

Nigeria rehabilitating freed Chibok girls

02:06

Now playing

- Source: CNN

Chibok school girls recently freed from Boko Haram captivity are seen in Abuja, Nigeria, Sunday, May 7, The 82 freed Chibok schoolgirls arrived in Nigeria's capital on Sunday to meet President Muhammadu Buhari as anxious families awaited an official list of names and looked forward to reuniting three years after the mass abduction.

82 Chibok schoolgirls freed from Boko Haram

02:22

Now playing

- Source: CNN

A Boko Haram flag flutters from an abandoned command post in Gamboru deserted after Chadian troops chased them from the border town on February 4, 2015. Nigerian Boko Haram fighters went on the rampage in the Cameroonian border town of Fotokol, massacring dozens of civilians and torching a mosque before being repelled by regional forces. AFP PHOTO/STEPHANE YAS (Photo credit should read STEPHANE YAS/AFP/Getty Images)

Who are Boko Haram?

01:03

Now playing

- Source: CNN

chibok girls timeline sfc orig_00010911.jpg

21 Chibok girls freed: Timeline of events

01:26

Now playing

- Source: CNN

This photo, obtained exclusively by CNN, shows some of the 21 girls who were released to the Nigerian military Thursday morning in Nigeria.

Boko Haram releases 21 missing Chibok girls

01:40

Now playing

- Source: CNN

amina ali nkeki chibok

Chibok girl who escaped in May gives message of hope

01:10

Now playing

- Source: CNN

A screengrab taken on May 12, 2014, from a video of Nigerian Islamist extremist group Boko Haram obtained by AFP shows girls, wearing the full-length hijab and praying in an undisclosed rural location. Boko Haram released a new video on claiming to show the missing Nigerian schoolgirls, alleging they had converted to Islam and would not be released until all militant prisoners were freed. A total of 276 girls were abducted on April 14 from the northeastern town of Chibok, in Borno state, which has a sizeable Christian community. Some 223 are still missing. AFP PHOTO / BOKO HARAM
RESTRICTED TO EDITORIAL USE - MANDATORY CREDIT "AFP PHOTO / BOKO HARAM" - NO MARKETING NO ADVERTISING CAMPAIGNS - DISTRIBUTED AS A SERVICE TO CLIENTSHO/AFP/Getty Images

Source: 21 Chibok girls released in Nigeria

01:31

Now playing

- Source: CNN

Chibok girl Amina Ali Nkeki (in red), who was kidnapped by Boko Haram and escaped after two years, with her baby and friend Serah Luka.

Escaped Chibok girl tells her story

02:05

Now playing

- Source: CNN

chibok hostage story busari pkg_00002812.jpg

Escaped girl: I still think about Boko Haram husband

01:29

Now playing

- Source: CNN

daughters of chibok boko haram jsten orig_00004526.jpg

Haunted by loss: Chibok parents share their stories

02:00

Now playing

- Source: CNN