MOGADISHU (Reuters) - A car bomb explosion in the southern Somali town of Kismayo wounded at least 10 people on Tuesday, police and residents said.

The blast occurred on a busy road in the port city once prized by warlords and the Islamist militant group al Shabaab for its money-spinning charcoal trade, said Mohamud, a police officer who gave his first name only.

“We believe it was a car bomb parked here in this busy street. So far we know 10 civilians were injured,” he told Reuters.

There was no immediate claim of responsibility. Al Shabaab, which has been frequently carrying out attacks in the country, was not immediately reachable for comment.

Residents gave a larger number of casualties, saying up to double the amount claimed by police may have been injured in the explosion.

“I could see about 20 people being transported into ambulances and pickup trucks as I ran away,” said Mohamed Isak, a resident of the city.

The blast is a rare attack in the lucrative port city once tightly controlled by al Shabaab. The group often targets the capital Mogadishu and bases operated by government and African Union (AU) soldiers in remote outposts.

Al Shabaab is waging an insurgency to overthrow the western-backed government and drive out the AU peacekeepers supporting it in a bid to take over the Horn of Africa country and impose its strict interpretation of Islam.

The insurgents ruled over large parts of the nation until 2011, when they were driven out of Mogadishu by the peacekeepers and Somali troops.