NAIROBI (Reuters) - Gunmen abducted two Cuban doctors near Kenya’s border with Somalia on Friday as they were going to work, and shot dead a police officer guarding them, authorities said.

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Local television station KTN News said police suspected the gunmen could be militants from Somalia’s al Qaeda-linked al Shabaab group. Kenyan Citizen television footage showed police setting up a roadblock on a road leading to the border.

National Police Service spokesman Charles Owino said gunmen in two Toyota cars stopped the vehicle carrying the Cubans as well as two police officers in the center of the town of Mandera.

One policeman was fatally shot by the attackers, and they then “commandeered the car and the occupants crossed the border to Somalia,” Owino told a news conference.

He said the vehicle, which belonged to the Mandera County hospital where the Cubans worked, had been recovered and the driver had been detained for interrogation.

The fate of the second policeman was not immediately known.

Owino did not say who was behind the attack and took no questions.

Al Shabaab has taken responsibility for a number of attacks in the border-area town in northeastern Kenya, in which dozens of civilians and security personnel have been killed.

In November, gunmen wounded five people, including two children, and kidnapped an Italian charity worker in Chakama, a small town near Kenya’s Indian Ocean coast south of the Somali border. The fate of the Italian woman is unknown.

Al Shabaab is fighting to topple Somalia’s central government and establish their own rule based on a strict interpretation of Islamic law.

The group also conducts frequent assaults in Kenya, mostly in the northern border region, to put pressure on the Kenyan government to withdraw troops from Somalia’s African Union peacekeeping force.

On Tuesday, the U.S. Embassy upgraded its warning against travel in Mandera County. “Exercise increased caution in Kenya due to crime, terrorism and kidnapping,” the warning read.