A powerful explosion has killed at least three people near the port of the Somali capital, Mogadishu, police say.
At least another seven people were injured, police added. The blast was followed by the sound of gunfire.
One report said a suicide bomber had targeted a tax collection facility at the port but this was not confirmed.
Images posted on social media show a cloud of smoke mushrooming over the city. No group has said it carried out the attack.
But the Somali Islamist group al-Shabab often carries out such bombings in the capital.
"So far, three civilians have died and seven others were injured,” Major Abdikadi Ahmed of the Somali police told Reuters news agency.
"The death toll may rise. There were porters and public vehicles queuing outside the gate when the blast occurred.”