Zimbabwe's military has seized power saying it was targeting "criminals" around President Robert Mugabe, the only ruler the country has known in its 37 years of independence.
Soldiers seized the state broadcaster. Armoured vehicles blocked roads to the main government offices, parliament and the courts in central Harare, while taxis ferried commuters to work nearby. The atmosphere in the capital remained calm.
The military said Mugabe and his family were safe. Mugabe himself spoke by telephone to the president of South Africa, Jacob Zuma, and told him he was confined to his home but fine, the South African presidency said in a statement.
It was not clear whether the apparent military coup would bring a formal end to Mugabe's rule; the main goal of the generals appears to be preventing Mugabe's 52-year-old wife Grace from succeeding him.
But whether or not he remains in office, it is likely to mark the end of the total dominance of the country by Mugabe, the last of Africa's generation of state founders still in power.
Mugabe, still seen by many Africans as an anti-colonial hero, is reviled in the West as a despot whose disastrous handling of the economy and willingness to resort to violence to maintain power destroyed one of Africa's most promising states.
He plunged Zimbabwe into a fresh political crisis last week by firing his vice president and presumed successor. The generals believed that move was aimed at clearing a path for Grace Mugabe to take over and announced on Monday they were prepared to "step in" if purges of their allies did not end.
"We are only targeting criminals around him (Mugabe) who are committing crimes that are causing social and economic suffering in the country in order to bring them to justice," Major General SB Moyo, Chief of Staff Logistics, said on television.
"As soon as we have accomplished our mission, we expect that the situation will return to normalcy."
Whatever the final outcome, the events could signal a once-in-a-generation change for the southern African nation, once one of the continent's most prosperous, reduced to poverty by an economic crisis Mugabe's opponents have long blamed on him.
Even many of Mugabe's most loyal supporters over the decades had come to oppose the rise of his wife, who courted the powerful youth wing of the ruling party but alienated the military, led by Mugabe's former guerrilla comrades from the 1970s independence struggle.
"This is a correction of a state that was careening off the cliff," Chris Mutsvangwa, the leader of the liberation war veterans, told Reuters.
"It's the end of a very painful and sad chapter in the history of a young nation, in which a dictator, as he became old, surrendered his court to a gang of thieves around his wife."
The opposition Movement for Democratic Change called for a peaceful return to constitutional democracy, adding it hoped the military intervention would lead to the "establishment of a stable, democratic and progressive nation state".