Al Shabaab gunmen attacked Kenyan police vehicles near Somalia's border, injuring at least five officers and burning five cars, police said on Tuesday.

Two officers were critically injured and three others sustained minor injuries in the attack in Garissa County, national Police Chief J.K. Boinnet said in a statement.

Garissa police commander Shadrack Maithya said at least 13 police officers who went missing during the attack have been accounted for. Two of the attackers were killed, he said.

The interior ministry said no police officials were killed, dismissing earlier accounts by two officials that several missing colleagues were believed to have been killed. Kenya's Daily Nation newspaper reported that at least 20 police officers were feared dead. Police later said that in the confusion of the attacks that the worst was feared.

The injured officers were part of team of more than 20 officers traveling in three pick-up trucks to recover a firearm lost by one officer whose car had hit a land mine.

Boinnet said there was a heavy exchange of gunfire with the Islamic militants. Al Shabaab, a Somali extremist group with links to Al Qaeda, said on its radio station that it carried out the attack.

Al Shabaab has carried out several attacks in Kenya in retaliation for Kenya's military involvement in Somalia.

In a separate incident Tuesday morning, suspected al-Shabab militants ambushed a vehicle carrying four passengers in Lafey in the northern county of Mandera, wounding at least one person before seizing the vehicle and driving it toward Somalia, according to an official who requested anonymity because he was not authorized to divulge the information.

The Kenyan military said late Monday that it had killed seven Al Shabaab members inside Somalia.

The group claimed responsibility for an assault last month on a college in Garissa town in which 148 students were killed, as well as a 2013 attack on an upscale mall in the capital, Nairobi, in which at least 67 people were killed.