Zimbabwe's military has placed President Robert Mugabe under house arrest in the capital Harare, South African President Jacob Zuma says.
Mr Mugabe told Mr Zuma in a phone call that he was fine, the South African leader's office said.
Troops are patrolling the capital, Harare, after they seized state TV and said they were targeting "criminals".
The move may be a bid to replace Mr Mugabe with his sacked deputy, Emmerson Mnangagwa, BBC correspondents say.
Mr Mnangagwa's dismissal last week left Mr Mugabe's wife Grace as the president's likely successor.
Heavy gun and artillery fire could be heard in northern parts of Harare early on Wednesday.
Mr Mugabe, 93, has dominated the impoverished country's political scene since it gained independence from the UK in 1980.
What do we know of Mr Mugabe's situation?
The firing heard during the early morning came from Harare's northern suburbs, where Mr Mugabe and a number of government officials live, the BBC's Shingai Nyoka reports from Harare.
In a statement, Mr Zuma's office said: "President Zuma spoke to President Robert Mugabe earlier today who indicated that he was confined to his home but said that he was fine."
<<Print>>