Soldiers have seized the headquarters of Zimbabwe’s national broadcaster and loud explosions and gunfire have been heard during a night of mounting tension in the capital, Harare.
An army general appeared on television to insist that there had not been a military coup and that the president and his family were “safe and sound”.
Live updates: Zimbabwe army takeover
What has happened?
There are reports of military vehicles blocking roads close to parliament in Harare, and outside the ruling Zanu-PF party headquarters.
Earlier, explosions and gunfire were heard in northern suburbs of the capital, including shots near 93-year-old President Robert Mugabe’s private residence.
Troops were said to have entered the headquarters of the national broadcaster ZBC, and Maj Gen Sibusiso Moyo then read out a statement on national television.
He assured the nation that President Mugabe and his family were safe, and insisted his security was guaranteed. The military was only targeting what he called “criminals” around the president, he said, denying that there had been a coup.
On Wednesday morning, a Twitter account which purports to be from Zanu-PF said there had been a “bloodless transition”:
Moments before, it claimed that the “first family” had been detained – this claim has not been corroborated.
On Tuesday, Zanu-PF officials accused army chief Gen Constantino Chiwenga of “treasonable conduct” over challenging Mr Mugabe over the sacking of Vice-President Emmerson Mnangagwa last week.
Zanu-PF said Gen Chiwenga’s stance was “clearly calculated to disturb national peace… and suggests treasonable conduct on his part as this was meant to incite insurrection”.
On Monday, Gen Chiwenga warned that the “purge” in the ruling party must stop or the army would step in.
What hasn’t happened?
There hasn’t been any response from the government to events – which could indicate that the Mugabes are indeed no longer in control, say analysts.
And there are no reports of any members of the security forces who remains loyal to Mr Mugabe, intervening to defend him. If it did, events could take a bloodier turn.
Is this a coup?
It’s been described as an “extraordinary overnight gamble” by BBC southern Africa correspondent Andrew Harding.
He says it is important to remember that Mr Mugabe is not being challenged by the Western governments he has warned against for decades, or by Zimbabwe’s political opposition, or by a mass uprising against economic hardship.
According to our correspondent “this is, fundamentally, an internal power struggle within the governing Zanu-PF party – and whoever emerges victorious can expect a newly purged party to fall, obediently, into line”.
In his TV address, Maj Gen Moyo said he wished to “make it clear that this is not a military takeover of government. We want to pacify a degenerating political social and economic situation in our country”.
He said the country would return to normalcy as soon as the military had accomplished what he called its “mission”.
What has upset those behind this action?
This is all about the leadership succession, as Mr Mugabe’s powers finally falter.
The people who fought in the 1970s guerrilla war against white minority rule still dominate Zimbabwe’s government, and especially its security forces, and they are worried about losing that power, and the wealth it generates.
In his statement on Monday, Gen Chiwenga warned against the “purging, which is clearly targeting members of the party with a liberation background”.
This was obviously a reference to the sacking last week of Mr Mugabe’s once loyal deputy, Mr Mnangagwa, a former defence minister, spy chief and veteran of the war of independence.
He and Grace Mugabe, who is four decades younger than her husband, had been seen as the main candidates to succeed Mr Mugabe.
Mrs Mugabe’s supporters are known as “Generation 40” or “G40” – a name which signals a changing of the guard in Zimbabwe, at least partially, 37 years after independence.
So this military action is the old guard reasserting its authority.
Mr Mugabe was the political leader of the guerrilla war so the army has always professed loyalty to him, until he explicitly came out in favour of his wife.
What is the mood in the country?
Zimbabweans have been posting on Facebook and Twitter that there has been no dramatic effect on normal life, though some reports say there is an uneasy calm in the capital, Harare.
People say that shops have opened as normal but there are few people on the streets of the capital.
A tweeter posted an update on his experience going to work.
Reaction across Africa
A statement from South Africa’s President Jacob Zuma calls for “calm and restraint”.
It appeals to the military to ensure that peace and stability in the country are not compromised.
He also says that he hopes there will be no unconstitutional changes, which, he says, would go against positions held by regional body Sadc and the African Union (AU).
The AU has not yet commented.