Al-Shabaab has vowed to carry out more attacks in Mogadishu following a vehicle bomb blast that killed scores of people in the Somali capital.

The warning came after the armed anti-government group claimed responsibility for Tuesday’s blast outside a government compound in Mogadishu, which killed at least 70 people and left many others wounded, officials and witnesses said.

“Somalis, we warn you: keep away from government buildings and the bases of their soldiers, more serious blasts are coming,” the Reuters news agency quoted Ali Mohamud Rage, an al-Shabaab spokesman, as saying.

An al-Shabaab member, speaking to the AFP news agency on condition of anonymity, earlier said one of the group’s fighters had carried out the attack.

“One of our mujahideen made the sacrifice to kill TFG (Transitional Federal Government) officials, the African Union troops and other informers who were in the compound,” the al-Shabaab member said.

The blast occurred when a truck blew up after coming to a halt at a security checkpoint at the entrance to the education ministry, Ali Hussein, a police officer in Mogadishu, said.

Sharif Sheikh Ahmed, the Somali president, said the attack had killed more than 70 people and left 150 injured.

“I am extremely shocked and saddened by this cruel and inhumane act of violence against the most vulnerable in our society,” Ahmed said in a statement.

Mohamed Sheikh Nor, a Somali journalist, told Al Jazeera that several ministers were coming out of the building at the time of the blast.

“It was the worst attack I have ever witnessed,” he said.

‘Cowardly act’

Ali Abdullahi, a nurse at Medina hospital, said medics were treating people with horrific wounds, including amputated limbs, burns, and patients who had been blinded by the blast.

“It is the most awful tragedy I have ever seen,” he said. “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.”

African Union and government troops deployed heavily to the area and cordoned it off.

The explosion is thought to have gone off as students were queuing for scholarships offered by Turkey, which recently stepped up its involvement in Somalia and pledged to re-open an embassy in Mogadishu.

Suldan Sarah, the communications director for the Somali president, told Al Jazeera that the majority of the victims had been students.

“To do a cowardly act like that does not mean you are a force to be reckoned with,” he said. “It just means you can commit a mass murder using a suicide bomber. This is not the sign of strength, but rather a cowardly act.”

He said the explosion happened outside a checkpoint at the complex of ministries, of which the Ministry of Education is a part.

“The security services are working around the clock, and are working within their capabilities, and as such have foiled a number of attempts over the past month (of other attacks),” Sarah said.

The attack was condemned by the U.N. chief, Ban Ki-moon.

“It is incomprehensible that innocents are being senselessly targeted,” Ban was quoted as saying by a spokesman, Martin Nesirky.

“The secretary-general is appalled by the vicious suicide bomb attack targeting government offices and ministries in Mogadishu today,” Nesirky said

Tuesday’s attack was the deadliest carried out by al-Shabaab since multiple bombings in the Ugandan capital Kampala killed at least 76 people in July 2010.

*Published under an agreement with Al-Jazeera.