Zimbabwe is under the control of the military two days after its army chief warned President Robert Mugabe against purging the ruling party's senior ranks.
Analysts say it appears to be the climax of a power struggle between liberation-era figures loyal to ousted vice president Emmerson Mnangagwa and forces faithful to First Lady Grace Mugabe, who is seen as vying to succeed her 93-year-old husband.
Here is what we know:
Military in control
Armoured personnel carriers and troops were deployed onto roads leading towards Harare on Tuesday, a day after army chief General Constantino Chiwenga warned the military may intervene after Mugabe fired Mnangagwa last week.
Mnangagwa was popular with security forces but had repeatedly clashed with Grace, 52, a political novice who is believed to have alarmed many senior army commanders with her open posturing and ambition.
It became clear after nightfall that the manoeuvres were not routine when the armoured vehicles took up positions outside key sites of power in the capital.
Shortly afterwards, a senior army officer, flanked by an air force commander, made a late night address on the ZBC state broadcaster after having apparently taken over the station's output.
They denied staging a coup, saying they were targeting "criminals" close to the president.
Initial reports suggest key Grace ally and leader of the ruling ZANU-PF party youth league Kudzai Chipanga is among those detained.
First family under siege?
During the late-night broadcast, the two uniformed commanders insisted that Mugabe was not under arrest.
"We wish to assure the nation that his excellency the president... and his family are safe and sound and their security is guaranteed," Major General Sibusiso Moyo said, reading out a prepared statement.
"We are only targeting criminals around him... this is not a military takeover of government."
The First Family have not been seen since the start of the unrest and prolonged gunfire was heard near Mugabe's private residence in the early hours of Wednesday morning.
The South African government said on Wednesday that President Jacob Zuma had spoken to Mugabe who confirmed that he was "confined to his home" -- but otherwise fine.
A security source told ANA that Mugabe has negotiated with Zimbabwe's military for Grace to leave the country and obtain “safe haven”, possibly in South Africa, in return for him giving up power.
The world responds
Zuma issued a statement calling for Zimbabwe to avoid "unconstitutional changes of government" and "urged the Zimbabwean Defence Force to ensure... the maintenance of peace and security".
Pretoria also announced it was sending its defence and intelligence ministers to Zimbabwe on behalf of the southern African regional bloc to meet army chiefs and Mugabe.
The European Union called on "all the relevant players to move from confrontation to dialogue."
The United States said its embassy would be closed to the public on Wednesday and called on its citizens in the country to "shelter in place".
Britain issued a special travel alert to call on its citizens to "avoid political activity", warning "the authorities have sometimes used force to suppress demonstrations".
The days ahead
The army's dramatic seizure of power from the ailing liberation leader turned autocrat has stunned the nation and plunged it into uncertainty.
Mnangagwa has reportedly arrived in Harare from South Africa on Wednesday to take control of the country’s government.
However South Africa's warning - together with its dispatch of envoys - could complicate any efforts to hand power to an unelected civilian caretaker government.
An extraordinary meeting of the ruling ZANU-PF party intended to smooth party divisions was scheduled for next month but this has now been thrown into doubt.
AFP and African News Agency