A deadly car bomb exploded close to the presidential palace in Somalia's capital Mogadishu on Monday, police said.
"So far, we know five soldiers died and over a dozen were wounded," Ali Hussein, a police officer, told Reuters, adding that the attack might have been aimed at a United Nations convoy that left the palace just before the blast. Hussein said it was a suicide attack.
There was no immediate claim of responsibility from the armed group Al-Shabab, which is trying to overthrow President Hassan Sheikh Mohamud's Western-backed government. Al-Shabab seeks to impose a strict version of Islamic law on the country.
Ahmed Aden, a resident in the area, said he had heard a loud blast followed by gunfire.
"Now we see huge smoke coming from the scene. Soldiers surrounded the area and we can only see ambulances rushing in and out," Aden said.
Mohamed Abdullahi, another police officer, told Reuters the attack may have been aimed at palace guards who sit in the area.
Al-Shabab stepped up attacks this month, retaking a town in the central region and attacking African Union troops.
Mohamud dismissed the capture of settlements by Al-Shabab fighters this month, saying they had no strategic value and it did not signal a resurgence of the group.
Al-Shabab retook the central Somali town of Buqda and two other southern settlements this month and has attacked African troops.
The raids follow a military campaign by African Union Mission in Somalia (AMISOM) forces and Somali troops that pushed the rebels out of towns on the coast and drove them into increasingly small pockets of countryside mostly in the south of Somalia.
"AMISOM and Somali National Army have liberated most of the major towns in Somalia and have taken over the strategic locations," Mohamud said last week in an interview in the capital Mogadishu.
"In the remote areas, Al-Shabab may move around to take over some smaller towns, but these are not strategic."
He said the group that had once ruled much of Somalia now had limited had access to the sea, which experts said had been used in the past to generate cash for the group from smuggling or importing arms.
Al-Shabab controls the Haradheere port town in central Somalia, but it lost control of Kismayu port in 2012.
"Al-Shabab is not regaining strength at all. It lost everything that could give it strength."
Western diplomats say the group is being slowly weakened, but can still pack a punch and threaten the pace of Somalia's gradual reconstruction and state-building process.
Just on Thursday, a blast claimed by Al-Shabab killed at least three soldiers who were waiting to collect their salaries at a military camp in Kismayu.
As well as attacking troops, the group frequently carries out bombings and gun attacks on officials at bureaus, hotels or restaurants.