(CNN) — The United States is assessing whether an airstrike against al-Shabaab in Somalia killed two Cuban doctors, as the terror group claims.

The U.S. carried out the airstrike on Thursday near Jilib in southern Somalia, according to U.S. Africa Command, a stronghold of the al-Qaeda affiliate.

In a statement shared by the SITE Intelligence Group, Al-Shabaab said that a U.S. drone strike hit a house in Jilib, killing the Cuban doctors Assel Herrera and Landy Rodriguez. It is the first time al-Shabaab has acknowledged holding the two Cubans hostage after kidnapping them from northeast Kenya nearly five years ago.

A spokeswoman for U.S. Africa Command says they are aware of the reports that two civilians were killed in the strikes.

“The command will continue to assess the results of this operation and will provide additional information as available,” said Lennea Montandon in a statement.

A U.S. defense official says there is no credible evidence that there were any civilian casualties in the strike, but they will continue to “investigate this allegation, as we take all such assertions seriously.”

The two doctors were kidnapped by al-Shabaab in Kenya in April 2019 in a brazen attack near the border with Somalia. A police officer who was escorting the doctors was killed in the attack. The doctors were in a government vehicle on their way to the hospital where they worked when they were taken hostage. At the time, Cuba’s Ministry of Health identified the doctors as Assel Herrera Correa, a specialist in general medicine, and Landy Rodriguez Hernandez, a surgeon.

Cuba and Kenya had an agreement to send doctors from Cuba to help with critical shortages of medical professionals in Kenya and to help implement universal healthcare coverage.

The U.S. has less than 500 troops in Somalia that assist the Somali government in their ongoing fight against al-Shabaab militants, including carrying out strikes on al-Shabaab targets. The U.S. considers al-Shabaab the largest al-Qaeda network in the world and one of the strongest, with the capability to attack US forces and US interests.