Nairobi - Five police officers were killed on Tuesday when their patrol was ambushed by suspected Shabaab Islamists in eastern Kenya, police said, the latest in a string of similar attacks in the area.The attack occurred in Ijara, in the county of Garissa, and led to a firefight between the officers - two of whom escaped - and their assailants."The five from Bothai police station were on patrol at 13:00 when they were ambushed by the terrorists on the Bothai-Ijara road, leading to a fierce gunfight," a senior police officer in Garissa said.Another senior officer at the regional police headquarters said the vehicle, a Land Cruiser, was burnt during the attack."We have a security operation going on there, and a helicopter has been dispatched to track the attackers who killed our officers," the officer said.Mohamud Ali Saleh, a local government official, confirmed the attack but did not give further details."There was an attack and some of our police officers have been killed," he said.Recent months have seen a spike in attacks on Kenya with a string of roadside bombs, most of them claimed by the Shabaab, leaving more than 20 police and a similar number of civilians dead since May.The Shabaab, an Islamic insurgency, is fighting to overthrow the internationally backed government in Mogadishu but also regularly carries out attacks in neighbouring Kenya, which has troops in Somalia as part of an African Union force.In its bloodiest single attack on Kenya so far, Shabaab gunmen raided a university in Garissa in April 2015 killing 148 people, most of them students, while in 2013 the group killed at least 67 people in an assault on a shopping mall in Nairobi.President Uhuru Kenyatta was re-elected last week, but opposition leader Raila Odinga claims the vote was rigged. Fears that Shabaab militants might seek to disrupt the election proved misplaced, with voting day passing peacefully across the country.