On Wednesday, after electoral officials announced that the ruling ZANU-PF party won most of the parliamentary vote, opposition supporters who claim Monday's poll was rigged took to the streets, burning tyres and throwing stones before riot police and the army intervened.
The opposition alleges the elections have irregularities, saying voting results were not posted outside one-fifth of polling stations as required by law.
Soldiers are now on the streets of Zimbabwe's capital, Harare, a day after they fired at demonstrating opposition MDC Alliance supporters who argued that the election results were being rigged.
The electoral commission had said it would start announcing results for the presidential race from 10.30 GMT, but this was delayed as commissioners read out more parliamentary results.
Four days later the ruling ZANU-PF party sacks him as leader and expels his wife.
Police spokeswoman Charity Charamba told state broadcaster Zimbabwe Broadcasting Corporation (ZBC) that the three people killed in the clashes had yet to be identified.
President Mnangagwa blamed the MDC Alliance leadership for the "violence and hooliganism", and ordered it to recall its protestors. "We don't accept that", Biti said.
"Zimbabwe's 2018 elections were conducted under an improved legal framework consisting of the 2013 constitution, The Electoral Act, other acts and legislation, rules and regulations promulgated by Zimbabwe Electoral Commission (ZEC)", said Boshe.
The riots surged up to the fence of the Rainbow Towers Hotel & and Conference Centre, where the electoral commission has been announcing results and many global election observers are staying. The opposition has raised fears about possible vote-rigging of the kind that marked past elections under former leader Robert Mugabe.
Wednesday's violence, which followed a relatively orderly election, dashes Mnangagwa's hopes of repairing the image of a country that had become synonymous with corruption and economic collapse under Mugabe.
Zimbabweans protest in downtown Harare.
The observer mission head said it was significant to note that there had been a "remarkable transformation in the exercise and protection of civil and political rights in Zimbabwe compared with the 2008 presidential run-off".
In Harare, the contrast could not be starker with November, when hundreds of thousands filled the streets, hugging soldiers and celebrating their role in ousting 94-year-old Mugabe, the only leader Zimbabwe had known since independence in 1980.
It said it had observed several problems, including media bias, voter intimidation and mistrust in the electoral commission, adding that there was an "improved political climate, but un-level playing field and lack of trust".
"Yesterday's events leave ordinary citizens with serious doubts that this government is any different from its predecessor, if not worse", the forum said, referring to the long rule of Mugabe, who resigned in November under military pressure.
In a late-night press conference on Wednesday, Home Affairs Minister Obert Mpofu warned further protests would not be tolerated.
Under Mugabe, elections were marred by fraud and often deadly violence, with the European Union mission banned since 2002.
Agents for all 23 candidates must verify them first, it said.