Somali security assess the scene of a bomb explosion at a checkpoint in Mogadishu. Feisal Omar/Reuters

A truck bomb exploded at a busy security checkpoint in Somalia's capital on Saturday morning, killing at least 78 people including many students, authorities said. It was the worst attack in Mogadishu since the devastating 2017 bombing that killed hundreds.

The explosion ripped through rush hour as Somalia returned to work after its weekend. At least 125 people were wounded, Aamin Ambulance service director Abdiqadir Abdulrahman said, and hundreds of Mogadishu residents donated blood in response to desperate appeals.

President Mohamed Abdullahi Mohamed condemned the attack as a "heinous act of terror" and blamed the local al-Shabab extremist group, which is linked to al-Qaida and whose reach has extended to deadly attacks on luxury malls and schools in neighboring Kenya.

On Sunday, US military officials said three airstrikes conducted against Al Shabaab militants in Somalia had killed four militants. The airstrikes came in coordination with the Somali government and, according to a US military statement, targeted Al Shabaab militants responsible for "terrorist acts against innocent Somali citizens.”

US Africa Command said an initial assessment concluded that two airstrikes killed two militants and destroyed two vehicles in Qunyo Barrow, and that one airstrike killed two militants in Caliyoow Barrow.

The truck bombing on Saturday targeted a tax collection center, police Capt. Mohamed Hussein said, as a large plume of smoke rose above the capital.

Associated Press