NAIROBI, Kenya (AP) A government official says unknown gunmen killed eight people, including five policemen, in an ambush in eastern Kenya.

Samuel Arachi, deputy inspector general of police, said Tuesday the eight died when a police car was sprayed with bullets 9 kilometers (5 miles) from the Kenya-Somalia border. Kenya's border area with Somalia has suffered attacks on government officials and non-Somali civilians since Oct. 2011 when Kenya sent troops into Somalia to fight the Islamic extremist al-Shabab rebels.

Al-Shabab, which is fighting Somalia's western-backed government, has vowed to retaliate against Kenya's military incursion. The group claimed responsibility for the Sept. 21 terror attack on a Nairobi mall in which at least 67 people died.

Musa Yego, the criminal investigations chief in Garissa County, said al-Shabab is suspected of carrying out Tuesday's attack.