A car bomb exploded on a busy street in the centre of Somalia’s capital Mogadishu on Saturday, causing an unknown number of casualties, police said.

There was no immediate claim of responsibility, although the Islamist al Shabaab group has carried out regular attacks.

“It was a truck bomb. It exploded at the K5 Junction,” said Mohamed Hussein, a police officer, referring to an area in the capital that is lined with government offices, hotels, restaurants and shops.

“There are casualties but we do not know the exact amount as the scene is still burning,” he told Reuters.

The al Qaeda-allied al Shabaab group is waging an insurgency to topple the weak UN-backed government and its African Union allies and impose its own strict interpretation of Islam.

In recent years, the militants have lost most territory under their control to African Union peacekeepers and government troops.

But they frequently launch deadly gun, grenade and bomb attacks in Mogadishu and other regions controlled by the federal government. Many attacks are aimed at military bases but some also target civilians.