Police officials: Al-Shabab militants hijack bus in northern Kenya, kill 28 non-Muslims

FILE - Armed members of the militant group al-Shabab attend a rally on the outskirts of Mogadishu, Somalia in this Feb. 13, 2012 file photo. Police officials say al-Shabab militants from Somalia have hijacked a bus Saturday Nov. 23, 2014 in northern Kenya and killed 28 non-Muslims on board. (AP Photo) (The Associated Press)

FILE - In this Thursday, Feb. 17, 2011 file photo, hundreds of newly trained al-Shabab fighters perform military exercises in the Lafofe area some 18 km south of Mogadishu, in Somalia. Suspected Islamic extremists from Somalia hijacked a bus at dawn near Mandera in Kenya's north near the border with Somalia, and killed 28 non-Muslims on board after they had been singled out from the rest of the passengers, police officials said Saturday, Nov. 22, 2014. (AP Photo/Farah Abdi Warsameh, File) (The Associated Press)

Police officials say al-Shabab militants from Somalia have hijacked a bus in northern Kenya and killed 28 non-Muslims on board.

The two police officers said Saturday that the bus traveling to the capital Nairobi was hijacked 50 kilometers (31 miles) from Mandera town. The officers say the gunmen singled out non-Muslims and shot them dead.

The officers insisted on anonymity out of fear of reprisals because of an order from Kenya's police chief that officers not speak to the media.

Kenya has been hit by a series of gun and bomb attacks blamed on Somalia's al-Qaida-linked al-Shabab militants since it sent troops into Somalia in October 2011. Authorities say there have been at least 135 attacks since then, including the Westgate Mall attack in which 67 people were killed.