The consequences of the attack are unclear but could impact on the ability of the opposition to campaign. Police on Sunday said an investigation continued and a "substantial reward" was offered for information.
Vice-President Mohadi is unbowed despite his injuries, he is in high spirits. I have just visited one of them who were left with his guts out; we hope he will be well.
Past votes have been marked by systematic intimidation of the opposition and fraud, and the U.S. and others have said a credible vote is key to lifting worldwide sanctions.
Mr Chiwenga's wife, Mary, Zanu-PF party chairperson Oppah Muchinguri-Kashiri and another party official, Ms Mabel Chinomona, were among senior officials injured in the attack.
Mpilo Hospital health clinical director, Solwayo Ngwenya said of the 29 people admitted at the hospital, 13 were discharged on Saturday night.
"They will observe the entire electoral process prior, during and after the harmonised elections, scheduled for July 30".
"Zimbabweans are vulnerable ... the electorate is vulnerable, political players like myself are vulnerable".
He said he "wishes a speedy recovery to those who were injured during this senseless act of violence, which can not be justified under any circumstances".
President Lungu said Bulawayo has been an area of interest in Zimbabwean politics, but hearing of such attacks on their Head of State made sad reading. "A team of observers will also be deployed to observe the elections", he said.
Footage from Saturday's event showed a device exploding and plumes of smoke billowing around Mnangagwa as he descended from the podium at the White City stadium in Zimbabwe's second largest city Bulawayo.
ZBC described the blast as "an assassination attempt". "Our thoughts & prayers go out to the victims & their families", reads the statement.