Emergency rescue staff carry the body of a victim over rubble at the scene of a car bomb attack, Feb. 4, 2019 in Somalia's capital Mogadishu. Getty

Somalia's homegrown extremist rebels, al-Shabab, claimed responsibility for a car bomb explosion on Monday that killed at least seven people in Somalia's capital. The terror group has been hammered by U.S. airstrikes in recent months, but continues to threaten the region sufficiently to prompt repeated warnings from Washington for Americans in nieghboring Kenya.

Al-Shabab said on its website that the attack was aimed at a gathering of government officials and security and intelligence personnel. At least nine people were also injured when the explosives-laden car parked near a mall close to Mogadishu's local government offices in the Hamarweyne district blew up, said Police Capt. Mohamed Hussein.

Al-Shabab, which is linked to al Qaeda, has been ousted from Mogadishu and most other urban centers in the south and central areas of the country, but the group continues to carry out deadly suicide attacks in Somalia and neighboring countries.

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Al-Shabab a persistent threat despite U.S. strikes

The U.S. Embassy in Nairobi, Kenya, warned U.S. nationals in a new security alert on Monday to be aware and report anything unusual, and to avoid areas frequented by Westerners in the capital city, as well as two other cities and along the country's coast.

"Credible information indicates Westerners may be targeted by extremists in Nairobi, Naivasha, Nanyuki, and coastal areas of Kenya," the Embassy said on Monday, without clarifying the nature of the threat. The alert stressed the need for heightened vigilance throughout Kenya, especially in public spaces such as shopping malls, hotels, and places of worship.

Al-Shabab was behind the brazen assault on a shopping and hotel complex in Nairobi just last month which left more than 20 people dead, including one American man. Kenyan intelligence officials told CBS News that the al-Shabab cell in Kenya which carried out that attack had been scouting the upmarket dusitD2 hotel complex for at least two years.

That was just the latest attack blamed on the group in Kenya, which has suffered repeated violence since sending forces across the border to Somalia to help in the U.S.-backed fight against the al-Shabab extremists.

The group remains a lethal threat in the region despite a dramatic ramping-up of the U.S. air war against the militants in Somalia. The Pentagon routinely sends official readouts on airstrikes targeting alleged al-Shabab training camps and outposts in the country -- the most recent of which was dated Feb. 2, describing a strike the previous day in southern Somalia which the military said had killed 13 terror suspects.

In June last year one member of the U.S. Special Forces was killed and three others wounded by an al-Shabab attack in Somalia, so while there is no open U.S. ground war going on, American troops are involved.

The pace of the airstrikes has been relentless, with U.S. missiles killing at least 109 alleged al-Shabab militants during January and the first few days of February alone.

"Somali security forces continue to keep pressure on al-Shabaab, creating conditions for further political and economic development," Maj. Gen. Gregg Olson, U.S. Africa Command (AFRICOM) director of operations, said in the press release about the Friday airstrike. "Somalia continues to demonstrate its commitment toward enhancing regional stability and security while degrading a transnational threat."

The AFRICOM release said no civilians were believed to have been harmed in the airstrike.