Gunfire erupted in Somalia's capital Mogadishu on Friday during a protest against delays to a national election.
Protesters woke to find Somalian government forces sealed off roads near the Unknown Soldier monument where the protest was to take place.
Opposition figure Abdirahman Abdishakur Warsame posted a video of himself leading a small crowd of protesters into the streets, in defiance of a government ban on demonstrations.
In the video, a group of marching protesters are seen running for cover after gunfire rings out.
Former prime minister Hassan Ali Khaire confirmed reports of shelling near Aden Adde airport and said part of it caught fire. Images on social media showed a large plume of dark smoke rising above Mogadishu.
Friday morning's incident came hours after fighters loyal to the government exchanged gunfire with groups allied to the opposition.
"Many forces heavily attacked us. I am now on my chest in an alley. This is a massacre," protester Farah Omar told Reuters.
President Mohamed Abdullahi Mohamed, better known by his nickname Farmajo, is under pressure as the February 8 election date came and went without resolution of issues related to how the vote is to be conducted.
A coalition of opposition candidates said they no longer recognise Farmajo as president and had vowed mass protests until he steps down, to begin on Friday.
Information Minister Osman Dubbe said "armed militia" attacked a military post in Mogadishu overnight but were repulsed.
But former president Sharif Sheikh Ahmed said the government raided the hotel near the presidential palace where he and another former president, Hassan Sheikh Mohamud, were staying.
"This attack is yet another example of the government's desperate attempts to suppress the voice of the people who oppose the federal government's failure to hold national elections," presidential candidate Abdinasir Abdille Mohamed said.
That political rivalries have expanded into open conflict will dismay Somalia's allies and plays into the hands of Al Qaeda-linked insurgents Al Shabab.
The UN mission in Somalia said it was "deeply concerned by armed clashes in Mogadishu overnight and on Friday morning".
The UN called for “calm and restraint by all parties involved” and open lines of communication to reduce tensions.