A truck bomb exploded at a busy checkpoint in the Somali capital Mogadishu during morning rush hour on Saturday killing at least 90 people, according to an unnamed international organization cited by Reuters. A Somali lawmaker also said in a tweet that the death toll was more than 90, including 17 police officers. Most of those killed were students returning to class, Mayor Omar Mohamud Mohamed said. Officials warned the death toll is likely to increase.

Saturday’s bombing was the deadliest attack in Mogadishu in recent years and the force of the blast reminded many of the devastating attack that took place in October 2017 when a truck exploded next to a fuel tanker and killed almost 600 people. Although no one has claimed responsibility for the bombing yet, all speculation immediately turned to al-Qaida-linked al-Shabab, which often carries out attacks in the country. Al-Shabab was blamed for the 2017 blast even though it never claimed responsibility.

Saturday’s blast, which took place just before 8 a.m. at an intersection that connects Mogadishu to the rest of southern and southwestern Somalia, was the latest in a series of attacks this year. It once again raised questions about the ability of Somali forces to secure the country as African Union troops are scheduled to withdraw from the country in mid-2020.