"At least three people were injured in the blast which targeted Turkish engineers," a police officer who requested anonymity told Xinhua.
Witnesses said they heard a huge blast near the headquarters of Mogadishu's Hodan district.
"The blast was huge and I felt panic. Everyone ran for his safety," a witness, Ahmed Abdi, told Xinhua on the phone.
There was no immediate claim of responsibility for the latest attack, which struck at about 05:30 p.m. local time.
Somalia is holding parliamentary elections.