GARISSA, Kenya - An al Qaeda affiliated Somali militant group said Thursday that it took several hostages in a raid in northern Kenya that killed at least six people.

Three policemen, a civil servant and a primary school teacher were among the six killed in the attack late Wednesday, said North Eastern Province Police Commissioner James ole Seriani. A pregnant woman was also killed, said relative Adan Gedi.

Seriani said at least four government officials are missing, including a district officer.

The press release from the Somali militant group al-Shabab did not specify how many hostages had been taken from the northern town of Gerille, near the Somali border, but said their identities would soon be released.

"In response to the aggressive Kenyan invasion against the Muslims of Somalia, special forces from Harakat Al-Shabaab Al Mujahideen's elite units raided a Kenyan Administration Police camp," the statement said. "Taken by surprise and unable to respond effectively to the attack, seven Kenyan administration police and government officials were immediately killed, while others were taken prisoners."

A Kenyan police spokesman did not respond to calls seeking comment.

Al-Shabab also said they captured vehicles, communication equipment and a cache of weapons. The seizure of a police vehicle and communication equipment was confirmed by the officer commanding the police division in Wajir, George Tonui.

Seriani said the militants had disabled police communications to prevent reinforcements from coming after they launched their attack. The militants came around sunset, as the Kenyan security services were holding prayers, said Sgt. Yusuf Osman, who was hospitalized with a bullet wound.

The raid follows a Kenyan army claim that they killed a high-ranking al-Shabab commander in southern Somalia last week, and the arrest of a man in the town that police said was charged with handling explosives.

Al-Shabab says the raid on a police camp was in response to Kenya's decision to send troops into Somalia in October.

Kenya said it sent in the troops after a string of attacks by Somali militants on Kenyan soil. But the militants deny the attacks, blaming them on freelance gunmen instead.

In a separate development, a British man and two Kenyans were on Thursday charged with handling explosive materials by a court in Kenya's coastal city of Mombasa. Jermaine Grant had already received a three-year jail sentence for being in the country illegally after using false documents that claimed he was a Canadian called Peter Joseph.

Police say the three were arrested along with a Kenyan woman in December in a house with chemicals commonly used to make bombs.

Grant's arrest was followed by a warning from the British government that it believed militants linked to Somalia's al-Shabab group were about to carry out a terror attack in Kenya.

Lawless Somalia has not had a functioning government for 21 years.