NAIROBI - Gunmen killed six Kenyans including four policemen and abducted three others, in the latest of a string of attacks in the northeastern region that borders Somalia, police said Thursday. Two other policemen were wounded in the attack some 10 kilometres (six miles) from Somalia — an area hit by a series of blasts in the three months since Nairobi sent troops into Somalia to fight Islamist Shebab insurgents. “Six people have been killed, and three others were abducted,” said regional police chief Leo Nyongesa, adding that the attack took place late Wednesday in Gerille in Kenya’s Wajir district.

Those killed included four police officers, a local government official and a civilian, he said, adding the attackers had used firearms and thrown an explosive device.

“There are others who have not been accounted for,” a senior police officer in the region told AFP on condition of anonymity.

“A major security operation is currently underway and a helicopter has been sent to search for 13 police officers missing after the attack.”

The three people reported abducted are believed to be local government officials, he added.

No group claimed responsibility, but Kenyan officials have blamed Somalia’s Al-Qaeda linked Shebab rebels and their sympathisers for previous bombings and shootings, although armed bandits also operate in border areas.

Human Rights Watch (HRW) warned Thursday that Kenyan security forces were abusing civilians and Somali refugees in northeastern regions following the spate of attacks since Nairobi sent troops into Somali in October.

Hand grenades have been thrown into bars and a church, while homemade explosive devices have been set off apparently targeting security forces.

“In response, members of the security forces have been responsible for rape, beatings, looting, and arbitrary arrests of civilians,” the New York-based rights group said in a statement Thursday.

“The crackdown has largely targeted Somali refugees and Kenyan ethnic Somalis, but residents of other ethnic backgrounds in North Eastern province have also been victimized.”

The most recent incident, HRW said, was the rounding up and beating on January 11 of residents of Garissa, the capital of North Eastern Province, in a local military camp.

“When military officers can beat civilians in broad daylight without fearing repercussions, it’s clear that impunity has become the norm,” said Daniel Bekele, Africa director at HRW.

“Repeated promises by both the police and the military to stop these abuses and investigate have amounted to nothing.”

Kenyan army spokesman Major Emmanuel Chirchir told HRW that he did not have knowledge of any abuses, but said that that the military would investigate the claims.

Victims told HRW that they were told to roll around on the ground then kicked and beaten with the butts of guns simply because they were going about their business in the vicinity of the military camp.

HRW said its researcher who attempted to visit the camp to speak to the officer in charge was denied access and “witnessed soldiers forcing several men to lie down in the dirt and forcing another man to frog-jump across the field and to assume various gymnastic positions”.

Gunmen have recently also targeted Dadaab, the world’s largest refugee camp about 100 kilometres south of Wednesday’s attack, which houses some 460,000 Somalis who have fled famine and war over the past two decades.

READ MORE: A leather jacket

Gunmen seized two Spaniards working for Medecins Sans Frontieres (Doctors Without Borders) from Dadaab in October and are thought to have taken them to Somalia.

The kidnapping of the Spaniards was one of the incidents that spurred Kenya to send troops to fight the hardline Shebab.

Regional armies are pushing against Shebab positions in Somalia, with Kenyan forces in the far south, Ethiopian soldiers in the west and African Union forces in Mogadishu made up of troops from Uganda, Burundi and Djibouti.