The United Nations has strongly condemned what it has described as a "horrendous" car bomb attack in the Somali capital, Mogadishu on Saturday that left at least 78 people dead, including many students.In a statement, UN Secretary-General Antonio Guterres extended his deepest sympathies and condolences to the families of the victims and wished a speedy recovery to those injured in the blast."He stressed that the perpetrators of this horrendous crime must be brought to justice," a statement by his spokesperson said. READ | Massive car bomb kills at least 76 in Mogadishu, death toll 'could still be higher'Saturday's blast was the worst attack in Mogadishu since the devastating 2017 bombing that killed hundreds.Police officer Mohamed Hussein said the blast targeted a tax collection centre during the morning rush hour. The explosion ripped through rush hour as Somalia returned to work after its weekend.'Bodies lying on the ground'At least 125 people were wounded, Aamin Ambulance service director Abdiqadir Abdulrahman said. Hundreds of Mogadishu residents donated blood in response to desperate appeals."The explosion was very large," an eyewitness said. "It was close to where the 2017 bombing happened.""I saw many bodies lying on the ground. In my eyes, some of the dead were police officers, but also students were killed."President Mohamed Abdullahi Farmaajo condemned the attack as a "heinous act of terror" and blamed the al-Shabaab armed group."Saturday's tragedy has become a lesson learned since the country is in a state of war, we need to be vigilant against the terror attacks, since the primary goal of terrorists is to cause maximum damage to everybody," he said."They are not only targeting those who work for the government but the entire population."On Sunday, Somalis mourned the deaths of young people in a country trying to rebuild itself after decades of conflict.Two Turkish brothers were among those killed, Somalia's foreign minister said.There was no immediate claim of responsibility, but al-Shabaab often carries out such attacks.The armed group was pushed out of Mogadishu in 2011 but continues to target high-profile areas such as checkpoints and hotels in the seaside city as well as in neighbouring Kenya.The capital was hit by its deadliest single attack in October 2017 when a truck bomb exploded, killing more than 500 people and wounding many more.Al-Shabaab was blamed for the truck bombing, but the group never claimed responsibility for the blast that led to widespread public outrage.Somalia has been riven by conflict since a civil war broke out in 1991, but has stabilised somewhat in recent years.The latest attack raises concerns about the readiness of Somali forces to take over responsibility for the country's security from an African Union force in the coming months.