A suicide car bomber crashed into a gate outside a hotel frequented by lawmakers in the centre of the Somali capital of Mogadishu on Wednesday and the attack was followed by gunfire, killing 15 people, police said.

Police said among the dead were two lawmakers. They had previously said at least 10 people were killed. Residents and a Reuters witness said gunfire could be heard in the area around the hotel late into the night.

"Lawmakers Mohamud Mohamed and Abdullahi Jamac died in the hotel. They lived in it," Major Ibrahim Hassan, a police officer, told Reuters. "Many other people including lawmakers were rescued. The operation is about to end now. So far the death toll we have is 15 dead and 20 others wounded."

Militants from al Shabaab, a group affiliated with Al Qaeda, quickly claimed responsibility for the attack on the Hotel Ambassador and said it had killed 20 people in addition to the two lawmakers.

"We targeted the members of the apostate government ... We killed many of them inside and we shall give details later. Our mujahideen are on the top floor of the hotel building," Sheikh Abdiasis Abu Musab, al Shabaab's military operation spokesman, told Reuters.

Authorities could not immediately verify Al Shabaab's statement.

Hassan had said earlier police suspected Al Shabaab fighters were still present in the hotel. State-run Radio Mogadishu had said government forces were still at the scene rescuing people from the hotel.

Al Shabaab was pushed out of Mogadishu by African Union peacekeeping forces in 2011. But it has remained a potent threat in Somalia, launching frequent attacks aimed at overthrowing the Western-backed government.

"I send condolences to the relatives of lawmakers Abdullahi Jamac and Mohamud Mohamed and likewise to the relatives of all those martyred in the barbaric attack," President Hassan Sheikh Mohamud, said in a statement.

"These barbaric attacks are aimed to frighten citizens so that they do not support governance and peace and that will never happen."

In February, at least nine people were killed when al Shabaab fighters set off a car bomb at the gate of a park near a hotel in the capital. In January, an attack on a beach-front restaurant killed at least 17 people.

Al Shabaab has also been behind deadly attacks in Kenya and Uganda. Both contribute troops to an African Union peacekeeping force in Somalia. - Reuters