At least 12 people were killed and more than 20 others injured when a car bomb exploded Thursday outside a restaurant in Somalia’s capital.

Witnesses tell VOA's Somali service the blast occurred outside the front door of a restaurant along Maka Al-Mukarama road, Mogadishu's busiest street.

“An explosive-laden vehicle was parked in a line of vehicles in front of the Bilsan restaurant, which was busy and at lunch time” said a witness who asked for anonymity.

“The roof of the restaurant collapsed with many people inside, I am not sure what has happened there and how many people were inside, but I can confirm six dead bodies lying the front street,” the witness said.

Authorities of Mogadishu’s ambulance services said at least six other people injured in the blast died on their way to hospitals.

There was no immediately claim of responsibility, but the attack bore the hallmarks of militant group al-Shabab, which frequently attacks hotels and restaurants in Mogadishu.

On Saturday, Shabab fighters stormed a government building in the capital and killed at least 15 people.

A surge in Shabab attacks and reports of suspected attacks have put Mogadishu residents on edge. Some analysts attribute the anxiety to the fact that a large number of militants fleeing from U.S. airstrikes on their rural bases have fled to Mogadishu.

Earlier, the U.S. Embassy in Somalia's neighbor Djibouti reported a security incident at Camp Lemonnier, the U.S. military base in Djibouti.

A spokesman for the U.S. Africa Command tells VOA there was a report of a suspicious package outside the installation.

"Camp personnel responded and determined there was no threat," said Major Karl Wiest. "Normal operations have resumed."