The UK government has urged for restraint and called for dialogue as fighting broke out in Somalia’s capital Mogadishu.
Rival units in the security forces and some former warlords and clan leaders clashed on Sunday.
The British embassy in Somalia said the violence reports were “deeply concerning”.
The international community has been calling for dialogue on the election impasse in the country after parliament extended President Mohamed Abdullahi Farmajo’s term by two years.
The protesters reportedly chanted: “We do not want a term extension. We do not want Farmajo. We do not want dictatorship.”
Former Somali president Hassan Sheikh Mohamud and opposition leader Abdirahman Abdishakur said pro-government soldiers had attacked their homes.
The government has since denied the accusations.
Somali Prime Minister Mohamed Hussein Roble called for negotiations after Sunday’s violence.