Opposition supporters in the capital, Harare, threw rocks and denounced the government, tearing down a billboard with an image of Mnangagwa and his campaign slogan: "The voice of the people is the voice of God". Soldiers shooting to kill, fleeing civilians.
The Zimbabwe Electoral Commission (Zec) has announced 122 seats for Zanu-PF so far, and 53 for MDC Alliance, ZBC state media reported.
In the weeks leading up to voting day‚ the MDC Alliance said it would not accept a vote that did not declare Chamisa as president.
The United Nations has urged political leaders and Zimbabweans to reject any form of violence.
Blood could be seen on the streets of Zimbabwe after police used live ammunition on civilians and protesters who accused the electoral commission of rigging results.
"The longer it lasts that the results of the presidential election is not known, the more lack of credibility it provides", Brok said.
"The results show beyond reasonable doubt that we have won the election and that the next president of Zimbabwe is Nelson Chamisa", said Biti, "We are however seriously concerned about evidence of interference... there is a deliberate delay in announcing the results".
Supporters of the opposition Movement for Democratic Change party react as they block a street in Harare, Zimbabwe.
President Emmerson Mnangagwa has urged patience and calm following the first elections since long-serving ruler Robert Mugabe was ousted from power.
Analysts have said it was unclear whether the country's generals, who ousted Mugabe and ushered Mnangagwa into office, would accept an MDC victory.
ZEC was expected to announce more results early this morning. "We won the popular vote (and) will defend it", Chamisa said on Twitter.
The rival claims pointed to a contested result, raising the prospect of competing fraud allegations and a possible run-off vote in September - required if no candidate wins at least 50 percent of ballots in the first round.
European Union observers on Wednesday said Zimbabwe's elections had several problems, including media bias, voter intimidation and mistrust in the electoral commission and questioned delays in releasing the presidential results, but the EU does not yet know if the shortcomings in the election will have a material impact on the result.
The regional SADC bloc, in its preliminary report, said Wednesday that the campaign and election had "proceeded in a peaceful and orderly manner and were largely in line" in Zimbabwean law.
His attempts to position Grace as his successor are widely thought to have driven the military to intervene and put their favoured candidate, Mnangagwa, in power.
Opposition leader Chamisa accused the ZANU-PF of trying to steal the election.
In 2008, then opposition leader Morgan Tsvangirai pulled out of the presidential run-off against Mugabe after attacks orchestrated by the state claimed the lives of at least 200 of his supporters.
Officers had been facing off through a locked gate against protesters who brandished opposition party banners, lit fires and chanted slogans against the ruling ZANU-PF party.