GARISSA: At least 147 students were massacred when Somalia's Shebab group attacked a Kenyan university on Thursday, the national disaster operations centre said after the deadliest attack in the country since US embassy bombings in 1998.

There are “147 fatalities confirmed in the Garissa attack,” the centre said in a statement.

“The operation at Garissa University College has ended, with all four terrorists killed,” the centre said, with the attack lasting some 16 hours from before dawn until well after dark.

Masked gunmen stormed the university in the northeastern town of Garissa as students were sleeping, hurling grenades and shooting dead others, before setting Muslims free and holding Christians and others hostage.

At least 79 people were wounded in the assault, which lasted for some 16 hours from when the first grenades were used before dawn to blast open the gates of the university, near the lawless border with war-torn Somalia.

In the final hour before darkness fell, Kenyan troops stormed the student dormitory where the gunmen were holed up as explosions and heavy gunfire rang out.

Local residents donate blood at Garissa hospital. -AP

“We are mopping up the area,” Interior Minster Joseph Nkaiserry told reporters, saying that four gunmen had been killed after Kenyan troops launched an assault on the final building.

“Unfortunately, we lost... a number of lives... it is in the region of 70 students, and 79 have been injured, nine of them critically. “It is the deadliest attack in Kenya since the 1998 bombing of the US embassy in Nairobi by Al-Qaeda, when 213 people were killed.

“The terrorists, 90 percent of the threat has been eliminated... we have been able to confirm that four terrorists have been killed,” Nkaiserry added, saying that troops were scouring the campus as the total number of gunmen was not known, but that the main operation was over.

The Al-Qaeda-linked Shebab claimed the pre-dawn attack, the same insurgents who carried out the Westgate shopping mall massacre in Nairobi in September 2013, when four gunmen slaughtered at least 67 people in a four-day bloodbath.

Shebab spokesman Sheikh Ali Mohamud Rage told AFP the gunmen had taken non-Muslims hostage, and that their mission had been “to kill those who are against the Shebab. “It was not clear if any of the students the Shebab said they had held were alive at the time of the final assault by troops. However, officials said over 500 students had been accounted for.

Students of the Moi University leave after escaping an attack. -AFP

“Kenya is at war with Somalia,” Rage said, referring to the thousands of Kenyan troops in Somalia as part of an African Union military mission.

Soldiers with tanks were deployed around the campus.

'Gunmen shot indiscriminately'

A $215,000 (200,000 euro) bounty was offered for the capture of alleged Shebab commander Mohamed Mohamud, a former Kenyan teacher believed to now be in Somalia and said to be the mastermind of the Garissa attacks.

The garrison town is around 150 kilometres (90 miles) west of Somalia and has in the past been targeted by militants from the Shebab.

Police chief Joseph Boinet said “the gunmen shot indiscriminately” after storming the compound.

The sprawling campus on the outskirts of town has both teaching areas as well as residential blocks. The university has several hundred students from different parts of Kenya.

Wave of attacks

A dawn until dusk curfew has been imposed on several northern and eastern Kenyan districts.

Kenya has been hit by a wave of grenade and gun attacks, often blamed on sympathisers of the Shebab and sometimes aimed at police targets, since the army crossed into southern Somalia in 2011 to attack militant bases. A series of foreign travel warnings in response to the threat have crippled Kenya's economically important tourism industry.

On Wednesday, just hours before the Garissa attack began, President Uhuru Kenyatta said Kenya “is as safe as any country in the world”.

On Thursday, he offered condolences to those killed, but said security forces had made the “appropriate deployment to the affected area. “However, he also ordered the “urgent” enrolment of a planned 10,000 police recruit boost, warning Kenya had “suffered unnecessarily due to shortage of security personnel. “British High Commissioner Christian Turner condemned the “cowardly” attack, while US ambassador Robert Godec called the killings “heinous”.

UN envoy to Somalia Nicholas Kay said the attack showed once again the “shocking brutality of Al-Shebab. “Kenya's government has been under fire since the Westgate attack. In June and July last year Shebab gunmen killed close to 100 people in a series of attacks on the town of Mpeketoni and nearby villages.

In November, Shebab claimed responsibility for holding up a bus outside Mandera town, separating passengers according to religion and murdering 28 non-Muslims. Ten days later 36 non-Muslim quarry workers were also massacred in the area.