Kenya launched airstrikes against Islamic militants in Somalia following an extremist attack on a Kenyan college that killed 148 people, a military spokesman said Monday.

Some relatives of those who died in the attack on the college gathered at a funeral home in Nairobi to view their loved ones. They prayed under an awning together and were led into the funeral home after an employee read out their names. Many emerged in tears.

Kenyan army troops on Monday walked through Garissa University College in the northeastern town of Garissa where the bloodiest attack by al-Shabaab on Kenyan soil occurred on Thursday. Shoes were scattered around and washed clothing still hung from a clothesline next to a dormitory.

Kenya's warplanes targeted the Gedo region of Somalia on Sunday afternoon and early Monday, said Col. David Obonyo of the Kenyan military. Gedo is directly across Kenya's border in western Somalia.

Kenya attack

A Kenya Defence Force soldier runs for cover near the perimeter wall during the al-Shabaab attack on a school campus in Garissa last week. (Noor Khamis/Reuters )

The planes bombarded the camps on Sunday but then noticed movement Monday and bombed again, said Obonyo.

The camps, which were used to store arms and for logistical support, were destroyed but it was not possible to determine the number of casualties because of poor visibility from the air, he said.

"This is part of continuing operations, not just in response to Garissa," said Obonyo.

"The planes were hovering around for a few minutes then started bombing the area," said Hawa Yusuf, a resident of Gabdon village, near Beledhawa town which is close to Somalia's border with Kenya.

"We don't know if there were any causalities," she said by phone.

"The planes struck a grassland where nomads often take their animals for grazing," said Ali Hussein, another resident of Gabdon.

"We are not aware of any military camps located there. They dropped bombs on the whole area," he said. Al-Shabaab fighters often use shrubby areas to conceal their fighters and transport.

Al-Shabaab, which is based in Somalia, claimed responsibility for the college attack Thursday in Garissa, saying it was in reprisal for Kenya having sent troops into Somalia in 2011 to attack al-Shabaab after gunmen carried out cross-border raids and kidnappings. Now those attacks in Kenya have increased, with civilians often being targeted.

Kenya's troops in Somalia are part of an African Union force and are also shoring up the beleaguered Somali government. Kenya has carried out airstrikes before.

Four al-Shabaab attackers were killed on Thursday to end the siege and their bullet-ridden bodies were later displayed in Garissa.

One of the attackers killed was a Kenyan, a law school graduate and a son of a government official in Mandera County, which borders Somalia.

Five people have been arrested on suspicion of involvement in the Garissa attack and one of them is a Tanzanian who was found hiding under a bed in the school, according to a police officer. Contradicting an earlier government statement, the Tanzanian was not armed with grenades, according to the police officer who insisted on anonymity because he is not authorized to speak to the press.

A leading member of parliament, Aden Duale, said work must be done to prevent Kenyan youths from becoming followers of extremism.

"Some of our youth have fallen victim to this evil ideology of al-Shabaab," he said. "We will embark on an immediate, massive and sustained campaign to win back the hearts and the minds of our youth within our constituencies and the countries as whole. We recognize that some of our religious institutions have had some role in radicalization and propagation of this ideology."

He also called for the closure of the Dadaab Refugee Camp, which houses nearly 500,000 who have fled Somalia.

The camp is the centre for the "the training, the coordination, the assembling of terror networks," claimed Duale, the majority leader in parliament. "These refugees, we want them relocated across the border . They have been with us for 20 years. I think time has come when the national security of our people becomes first."