THE death toll from Al-Shabaab militants’ Thursday morning attack on a university in Kenya some 150-km east of its border with Somalia, has risen to least 147 people, as the Kenyan government said the operation to neutralise the attackers had ended.

The country’s interior Interior minister Joseph Nkaiserry said that all four gunmen had been killed after Kenyan troops launched an assault on the final building where the insurgents had holed up for over 12 hours.

“It is unfortunate we lost 147 lives,” he said. Figures of those injured were not immediately available, while four security forces were also confirmed dead.  

The masked gunmen began the assault before dawn, using grenades to blast open the gates of the university in the northeastern town of Garissa, near the lawless border with war-torn Somalia, before attacking students as they slept.

This becomes the east African country’s worst terror attack since 1998, when Al-Qaeda terrorists bombed the US embassy, and surpasses the Westgate mall siege of Nairobi in 2013, where at least 67 people were killed.

The gunmen divided students at the northeastern Garissa University between Muslims and non-Muslims, letting the Muslim students go, insurgent spokesman Sheikh Ali Mohamud Rage told news agency AFP by telephone.

The institution is the only place of higher learning in the region.

Al-Shabaab militants have carried out a number of attacks in Kenya since October 2011, when Kenyan troops crossed over into Somalia to help fight the militant group.

Kenya has offered a $220,000 reward for Mohammed Mohamud Kuno, a suspected member of Al-Shabaab on a government watch list who authorities believe helped organise the attack.

Al-Shabaab is fighting to create an Islamic state in Somalia and is said to have divided loyalties over whether to follow Boko Haram’s lead and pledge loyalty to the Islamic State (IS) or retain allegiance to Al-Qaeda.

Recently Uganda confirmed a terror threat from the group, which targets countries that have contributed troops to the African Union’s Somalia mission which seeks to defeat the group.

Kenya is planning to build a wall to keep out the militants, who regularly cross the porous border.

We look at other major attacks in Kenya since 2011:

October 24, 2011—Two grenade attacks in downtown Nairobi leave at least six people dead and nearly 70 injured. These appear to be the first retaliatory attacks following Kenya’s incursion into Somalia. In the next two months several other attacks are launched, with churches among those targeted. At least nine attacks in December are blamed on the militants.

March 10, 2012—The year gets off on the same note, with at least five attacks in the first two months of the year. But in March at least six civilians are killed and more than 60 injured after grenades are thrown into a busy bus station in Nairobi.

June 24, 2012—A grenade is set off in a Mombasa bar packed with football fans, killing three and injuring 30. In the three months before at least six other attacks kill three people and injure tens of others.

July 1, 2012—At least 17 people are killed and 50 injured when masked gunmen attack two churches in Garissa, the setting of the latest attack.

August 28—Three policemen are killed in Mombasa and at least 12 injured following riots that attend the killing of Islamist cleric Aboud Rogo Mohammed. The preacher was alleged to be radicalising youths, the first in a number of unexplained killings of clerics in the Kenyan coast. Three weeks earlier US secretary of state Hillary Clinton had visited the country.

November 18, 2012—Ten people are killed and 25 injured when an explosive goes off in public transport mini-van, sparking looting and a stand-off in Eastleigh, a Somali-dominated neighbourhood in Nairobi

December 7, 2012—Five people die and eight others are injured in an explosion at a mosque in the same area of Nairobi, including the area MP Abdi Yusuf Hassan. Two days earlier another explosion had killed one person and wounded six. At least four other people die in terror attacks that month.

January 16, 2013—Suspected Islamic militants kill five people and injure three others in the hotspot city of Garissa. At least five other people die in other attacks that month

April 18, 2013—At least six people are shot dead in a hotel in Garissa in an attack carried out by four men. 10 others are wounded

September 21, 2013—At least 67 people are killed and 175 others injured in a four day siege of the upmarket Westgate shopping mall in Nairobi, which is popular with expatriates. Among the dead in the attack that caught the world’s attention was a relative of president Uhuru Kenyatta. 

December 14, 2013—Four people die and 36 are wounded after a grenade is thrown into a public mini-van in Eastleigh, Nairobi. Nine other people die in attacks that month.

March 31, 2014—Six people are killed in two explosions in Eastleigh, Nairobi 

April 1, 2014—Six people die in Nairobi’s Eastleigh are in two separate explosions. Three weeks later a car explodes at a police station in the area, killing its four occupants.

May 16, 2014—At least 10 people die in twin explosions in a crowded market in Nairobi. Six other people die that month, with nearly 70 hurt in other attacks.

June 16, 2014—At least 48 people are killed when Shabaab militants storm the coastal town of Mpeketoni in another attack that captures world attention

November 22, 2014—Gunmen attack a bus headed to Nairobi from Mandera, killing 28 persons mainly teachers and civil servants. Those dead are reported to have failed to recite Koranic verses

December 2, 2014—Al- Shabaab militants kill another 36, quarry workers ambushed in their sleep in Mandera. The majority are non-Muslims.

April 2, 2015—At least 147 killed as four Al-Shabaab gunmen storm a university in Garissa, in what is Kenya’s worst terror attack since 1998, when 213 people died in bombings at the US embassy.