At least 90 people died and scores more were wounded when a car bomb exploded at a busy checkpoint in the capital, Mogadishu. Many of the victims were students.
UN chief António Guterres has condemned what he described as "this horrendous crime", according to a statement issued by his spokesman.
Mr. Guterres has also extended his deepest sympathies to the victims and wished a speedy recovery to those injured in the blast.
"The Secretary-General reiterates the full commitment of the United Nations to support the people and Government of Somalia in their pursuit of peace and development," said the statement.
The top humanitarian official in Somalia also joined the Secretary-General in condemning the attack.
Adam Abdelmoula, who is a Deputy Special Representative at the UN Assistance Mission in the country, UNSOM, took to Twitter to underline the Organization's solidarity with the Somali people and Government.