In the first incident, two bombs planted in a livestock market in Afgoye town in Lower Shabelle region killed at least four people, police and residents said.
"One bomb exploded but caused no casualty, then a second bomb exploded, killing four civilians," Police Captain Nur Farah told Reuters from Afgoye.
The second explosion in the port town of Marka Wednesday killed nine people including a senior local government official in a suicide bombing in southern Somalia claimed by the Al-Shabaab jihadist group, police and witnesses said.
The attack occurred outside the administrative office where the district commissoner Abdullahi Ali Ahmed Wafow was speaking with local people, police said.
"Commissioner Abdullahi Wafow was killed in an explosion together with eight other people, most of them security personnel," a police officer in Marka, Ibrahim Ali, told AFP by phone.
"The police are still investigating the incident but there are already indications that a suicide bomber carried out the deadly attack."
"The bomber ran up to the commissioner and blew himself up," witness Abdukadir Hassan said.
Ahmed Farah, a Marka resident, said security personnel had sealed off the scene of the blast.
Al Shabaab military spokesman Abdiasis Abu Musab said the Islamist group was behind both attacks.
"We killed in an attack the Marka district commissioner and those with him. In Afgoye we killed two soldiers in an explosion," Musab told Reuters.
Al Shabaab has been fighting for more than 10 years to dislodge the country's central government and establish rule based on its strict interpretation of Islam's sharia law.
The group frequently carries out gun assaults and bombings of both military and civilian targets in Somalia and has also carried out attacks on regional targets, especially in neighboring Kenya.