A car bomb exploded in the heart of the Somalian capital Mogadishu on Wednesday, wounding two people and triggering bursts of gunfire from police, witnesses said.
The blast adds pressure on the embattled UN-backed government struggling to secure the city against al Qaeda-linked Islamist rebels, even with the help of nearly 10,000 African troops.
The blast happened in Mogadishu's busy administrative district. The police said four suspects had been detained.
"A car bomb has just exploded in Maka al Mukarram road. Then the police opened fire," resident Hussein Omar told Reuters.
Witnesses told Reuters the car had been parked on the street, arousing the suspicions of security forces who blocked off traffic.
"We got a man with the remote control seconds after he detonated the car. We also arrested three other suspects," police spokesman Abdullahi Barise said.
A Reuters photographer who saw the wreckage of the car, said one of the victims had been taking photos of the 4x4 vehicle at the time of the explosion.
The man who was bleeding heavily cried out in pain as onlookers helped him. One family had fled their house just metres away moments before the bomb blew up.
There was no immediate claim of responsibility. However, suspicion is likely to fall on Somalia's al Qaeda-linked al Shabaab militants, who are fighting a five-year long insurgency and control big chunks of central and southern Somalia.
There has been a surge in suicide bombings and remotely detonated blasts in Mogadishu since al Shabaab pulled most of its fighters out of the coastal city, vowing to turn increasingly to al Qaeda-inspired tactics.
Al Shabaab carried out a truck bombing in October which killed more than 70 people, the group's most deadly attack since launching their rebellion in 2007.
The militants have been weakened in past months, on the back foot against African Union soldiers in Mogadishu and losing territory to Kenyan and Ethiopian forces in the south. There are also signs of growing internal divisions within the rebel ranks.