Initial reports claim at least 10 people have been killed by a vehicle bomb attack.
"The death toll may rise further; most of the dead are civilians", Police Capt. Mohamed Abdi said.
"Our security forces captured the head of Amniyat Abdiwahab Khalif Ahmed in Bakara market in Mogadishu following a tip off from the public", said the minister.
The attack, claimed by the al-Qaeda-affiliated al-Shabab group, targeted a government building, a government official said.
More to follow soon.
Al-Shabaab militants claimed responsibility for a massive suicide bomb attack at a government building in Mogadishu Tuesday that killed up to 10 people and injured at least 20 others.
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"This is the man who organises the killing of civilians and suicide attacks in the capital, and we succeeded in capturing him this morning", said Abifutah Omar Halane, the spokesperson for Mogadishu's mayor.
According to an official, a huge explosion was heard in the Wadajir district of the capital.
The Shabaab group, which wants to impose a Taliban-style rule on Somalia, has been fighting for the last decade to overthrow successive internationally-backed governments in Mogadishu.
"There are government and their staff who have died at the scene".
Al-Shabab past year became the deadliest Islamic extremist group in Africa, with more than 4,200 people killed in 2016, according to the Washington-based Africa Center for Strategic Studies.
It has also launched attacks in Kenya and Uganda, both contributors to a 22,000-strong African Union force in the country.