Gunfire has erupted in Somalia's capital between soldiers loyal to the government and others angry at President Mohamed Abdullahi Mohamed over the leader's extended stay in power.
The gunfire heard across much of Mogadishu highlighted earlier warnings that the election standoff could increase instability in the Horn of Africa nation.
The estimated hundreds of mutinous soldiers, still in uniform, took up key positions in northern Mogadishu as some residents hid.
Somalia's security minister Hassan Hundubey Jimale expressed condolences to all victims but didn't say how many people had been killed or wounded.
He accused "some people who are not interested in the security of their people" of launching an attack in Mogadishu and said security forces had repulsed them.
The president faces growing opposition in Somalia and abroad after the lower house of parliament approved a two-year extension of his mandate and he signed off on it, to the fury of Senate leaders and vocal criticism from the international community.
Somalia's election, meant for early February, has been delayed amid disputes between the federal government and the states of Puntland and Jubbaland along with the opposition.
"Tonight's unacceptable violence is instigated and led by forces that want to send Somalia back to its dark past," the federal government said in a statement.
"Militia and foreign interference have combined to frighten the Somali people into submission."
The soldiers were believed to have entered the city from military bases outside Mogadishu.
Most of them belong to the clan of former presidents Hassan Sheikh Mohamud and Sharif Sheikh Ahmed.
Both have vowed to forcefully dislodge the president if he does not return to negotiations over the election delay or resign.
Former president Mohamud in a tweet alleged that forces loyal to the president had attacked his house.
"I've warned and am now repeating how dangerous it is to politicise security. (Mohamed) will shoulder the responsibility of whatever happens as a result of this," he said.
Somalia's internal security minister denied that.
A few hundred demonstrators gathered on Sunday chanting "We don't want dictatorship!" and burned the president's photo.