A vehicle carrying men in the uniforms of government security forces exploded in a main market in the Somali capital Mogadishu on Tuesday and gunfire could be heard afterwards, witnesses said.
Some witnesses said the casualties were carried away by other security forces, but it was not immediately clear if there were any fatalities. Police said they were gathering details.
There was no immediate claim of responsibility.
Somalia's Islamist al Shabaab rebel group, which has launched several attacks in Mogadishu, threatened last month to press its campaign after launching an assault on July 19 against a United Nations base that killed 22 people.
"A four-wheel-drive car carrying men in government uniform exploded in ... Bakara (market)," said one witness, Hussein Nur, a money exchanger.
"Immediately gunfire opened up. We are not sure who is doing it. The men in the car looked like soldiers," he said.
A Reuters witness at the scene said he saw the ruined car and quoted other witnesses as saying that they saw soldiers in it. There was no sign of casualties when he reached the spot.
Somali news leader