Guards at Hotel Sahafi and CID officers opened fire after the blasts, police added. Then, about 20 minutes later, a third explosion hit the busy street, witnesses said.

It was too early to give details of casualties, Mohammed Hussein, a police officer, told Reuters.

"The blasts targeted Hotel Sahafi which is just opposite the CID,” he said.

No group immediately claimed responsibility, but Islamists from the al Qaeda-linked al Shabaab group have mounted regular attacks in the capital.