al Shabaab has warned civilians to stay away from government buildings and military bases in Somalia, because they are planning more attacks.
At least 70 people were killed when a suicide bomber drove a truck loaded with explosives into a gate near a government compound on Tuesday. More than 50 people were wounded.
It was the largest attack since al-Shabab withdrew its forces from Mogadishu in August.
Planning Minister Abdullahi Godah Barreh told the BBC the building housed eight ministries and almost half the cabinet.
He said the area was protected, "but unfortunately, it was not good enough".
Al-Shabab controls large parts of south and central Somalia.