There was no immediate claim of responsibility, however al-Shabab militants, who want to topple the government, have carried out similar attacks in the past, China Daily reported.
“So far we know three of the security forces died. We believe al Shabab is behind the attack,” Mohamed Ahmed, a police officer, told Reuters.
He said the death toll was likely to go up because the bomb was powerful and it had caused damage even to nearby residential buildings.
A photographer at the scene saw the burnt-out shell of the bomber’s car and another vehicle nearby on fire.
Nearly 300 members of Somalia’s federal parliament were sworn in last week and they are expected to pick a new president.