At least 100 people were killed and 300 injured in two car bombs that exploded outside the education ministry in Somalia's capital Mogadishu on Saturday, the country's president said in a statement early on Sunday.

"Our people who were massacred ... included mothers with their children in their arms, fathers who had medical conditions, students who were sent to study, businessmen who were struggling with the lives of their families," President Hassan Sheikh Mohamud said after visiting the site of blast.

No one immediately claimed responsibility for the attack, although the president blamed the Islamist group al Shabaab. Al Shabaab typically avoids claiming responsibility for attacks that results in large numbers of casualties.

The first of the explosions hit the education ministry near a busy junction in Mogadishu. The second occurred as ambulances arrived and people gathered to help the victims.

The blast wave smashed windows in the vicinity. Blood covered the tarmac just outside the building.

The attack took place at the same place as Somalia's largest bombing, which killed more than 500, in the same month in 2017. In that blast, a truck bomb exploded outside a busy hotel at the K5 intersection, which is lined with government offices, restaurants and kiosks.

Mohamud said the number of victims could rise. He had instructed the government to provide immediate medical assistance to the injured, some of whom were in serious condition.