Kenya's military launched air strikes against the militant group al-Shabaab on Sunday night in the country's first response to the group's slaughter of dozens of students at Garissa University College last week.

Two al-Shabaab camps were destroyed in the air strikes carried out in Somalia's Gedo region, which the militants often use to cross over into neighboring Kenya, military officials told the BBC.

"The bombings are part of the continued process and engagement against al-Shabaab, which will go on," David Obonyo, spokesman for the Kenyan army, told the BBC.

Al-Shabaab, which has ties to al-Qaeda, stormed the university in the city of Garissa on the morning of April 2 as students slept and others carried out Christian services. Witnesses said the gunmen targeted Christian students as they open fired in the university's dormitories, killing 148 people.

It was the deadliest attack al-Shabaab carried out in Kenya. The group claims to be at war with the east African country for sending troops into Somalia to help peacekeepers fight the rebels.

Kenyan President Uhuru Kenyatta swore to respond to the assault "in the severest way possible," the BBC reported. But on Monday al-Shabaab refuted the military's claim its camps were destroyed and said the bombs hit farmland instead.  

"Kenya has not targeted any of our bases," Sheikh Abdiasis Abu Musab, a spokesman for the group, told Reuters.

Whether or not Kenya's fighter jets struck the intended targets, grieving Kenyans say the government was too slow in its response to the massacre.

"(The security services) waited too long and the terrorists had so much time to kill our kids," Isaac Mutisya, who lost his 23-year-old daughter on April 2, told Reuters.  

Over 400 Kenyans have been killed in the last two years in attacks carried out by al-Shabaab, which demands Kenya to withdraw from Somalia. Kenya has not shown any sign it will back down.