Nairobi, Kenya -- Suspected Somali al-Shabab Islamic extremists kidnapped two Cuban doctors on Friday and killed their police protection officer in northeastern Kenya, police sources said. The sources said the two doctors and their guard were on the way to work in the town of Mandera when they were attacked.

"It just happened this morning. The police officer is dead but the two doctors were taken away," a senior police officer, who asked not to be named, told AFP. "From the modus operandi and the fact that they went towards the Somalia border, we have reasons to believe that the kidnappers are al-Shabab."

Some 100 Cuban doctors follow proceedings during their induction program at the Kenya School of Government, June 11, 2018 in Nairobi. Getty

The two doctors are part of a group of about 100 Cubans who came to Kenya last year to help boost health services.

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Al-Shabab terrorizes despite U.S. strikes

Al Qaeda-linked al-Shabab militants have been waging an insurgency against Somalia's foreign-backed government for over a decade, and while it has lost some ground, the group continues to stage deadly attacks in both Somali and neighboring Kenya.

The terror group continues to threaten the region despite being hammered by U.S. airstrikes in recent months, prompting repeated warnings from Washington for Americans in Kenya.

Most recently, the terror group claimed responsibility for a car bomb attack in Mogadishu in February that killed at least seven people. Before that, Kenyan investigators confirmed that one of the suspected al-Shabab extremists involved in a devastating attack on a hotel and shopping complex in Nairobi, the Kenyan capital, had been identified as the son of a Kenyan military officer.

Some 21 people, including a police officer, were killed by the attackers. Intelligence officials in Kenya confirmed to CBS News that the al-Shabab cell had been scouting the upmarket dusitD2 hotel complex since at least December 2016.