The incident happened shortly after President Emmerson Mnangagwa had finished addressing the gathering.
ZIMBABWEAN President Emmerson Mnangagwa survived a blast at a ruling ZANU-PF party rally today, his spokesman said, adding that the leader has been taken to safety.
Mnangagwa took power in November after longtime leader Robert Mugabe stepped down under military pressure.
The health minister says there were no fatalities in the blast while numerous wounded are being treated in hospital. The strongest response to hate is love. There have been frequent allegations of assassination attempts directed at Mnangagwa and other senior politicians, though none of these have involved bombings or firearms.
The country's two vice presidents were among the injured, the state-run newspaper The Herald reported.
Nevertheless, Bulawayo - an opposition stronghold - remained calm last night with no evidence of reinforced security forces, local journalists said.More news: IPhones will soon be able to share exact location of 911 calls
"It's not the first attempt of my life". He said Saturday's "senseless act" would not get in the way of the upcoming elections.
It was not clear who was responsible for the explosion, which Mnangagwa called a cowardly act, or how the security around the president was breached.
Earlier, Ethiopian officials said one person has died and dozens more are injured, after an explosion at a rally for the new PM Abiy Ahmed.
Chiwenga's wife was also hospitalized, but she has been treated and released, Charamba said. "Our thoughts and prayers go out to the victims and their families", the embassy said in a message posted on Twitter.
The ministry expressed the UAE's solidarity with Zimbabwe against all forms of violence.
Mnangagwa, a longtime Mugabe ally whose firing as his deputy after a ruling party feud led to the transfer of power, is under pressure to deliver a credible vote that Western countries see as key to lifting worldwide sanctions.