Islamic militants detonated a truck bomb outside Somalia's Ministry of Education Tuesday, killing at least 70 people.
Dozens of others, including parents and students who were waiting on word of scholarships, were wounded in the attack.
The vehicle blew up after pulling up to a checkpoint at the entrance to the building, according to witnesses.
Ali Abdullahi, a nurse at Medina hospital, said they were treating people with horrific wounds, including amputated limbs, burns, and patients who lost their sight in the attack.
"It is the most awful tragedy I have ever seen," he said. "Imagine dozens are being brought here minute by minute. Most of the wounded people are unconscious and others have their faces blackened by smoke and heat."
"The explosion has not only affected the targeted place, but even passer-by people and car passengers died there," Ali Muse, chief of Mogadishu's ambulance service, said.
"The death toll may increase and we are still carrying many dead bodies," he said.
The blasts shattered more than a month of relative calm in Mogadishu. The al-Qaeda-linked militant group al-Shabab has claimed responsibility for the attack on one of its websites.
"Our Mujahideen fighters have entered a place where ministers and AMISOM foreigners stay," al-Shabab said in a post on a website.
They were referring to the Ugandan and Burundian forces who make up the African Union peacekeeping mission.
The bomb was the biggest attack since the insurgent group withdrew from the city two months ago. It was not clear whether the ministry building was their intended target.
The Somali government said that no senior government official was wounded in the bombing.