The blasts came a day before the first anniversary of a truck bombing that left more than 500 dead in Mogadishu, the worst ever attack in Somalia which was blamed on militant group Al-Shabab.
The death toll has risen to 20 people on Sunday following two suspected suicide bombers that struck in the southern Somali city of Baidoa on Saturday, a local hospital official said.
"We received 20 dead people and about 40 others injured from the twin blasts of yesterday," Abdifatah Hashi, the general manager of Baidoa city hospital told reporters on Sunday.
Al Qaeda-affiliated Al Shabaab militants, who want to topple Somalia's Western-backed central government, claimed responsibility for the attacks.
"What seems to be two suicide bombers blew themselves up in two restaurants in Baidoa," Ali Aden, a police officer in the city, said on Saturday.
Residents of Baidoa told Reuters they heard two loud blasts in the early evening, followed by huge plumes of the smoke.
The Al Shabaab militants had targeted the two restaurants because they were frequented by government troops, Abdiasis abu Musab, the group's spokesman for military operations, told Reuters.
The attacks follow a US air strike against Al Shabaab militants in Haradere, a district in Galmudug region.
The US military's Africa Command said on Saturday it was still assessing the impact of the strike, which was carried out on Friday together with the Somali military.
Somalia has been engulfed by violence and lawlessness since the early 1990s after the toppling of dictator Mohamed Siad Barre.